Polymerisable compounds and the use thereof in liquid-crystal displays

ABSTRACT

The present invention relates to polymerisable compounds, to processes and intermediates for the preparation thereof, to liquid-crystal (LC) media comprising them, and to the use of the polymerisable compounds and LC media for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the polymer sustained alignment type.

The present invention relates to polymerisable compounds, to processesand intermediates for the preparation thereof, to liquid-crystal (LC)media comprising them, and to the use of the polymerisable compounds andLC media for optical, electro-optical and electronic purposes, inparticular in LC displays, especially in LC displays of the polymersustained alignment type.

BACKGROUND OF THE INVENTION

One of the liquid-crystal display (LCD) modes used at present is the TN(“twisted nematic”) mode. However, TN LCDs have the disadvantage of astrong viewing-angle dependence of the contrast.

In addition, so-called VA (“vertically aligned”) displays are knownwhich have a broader viewing angle. The LC cell of a VA display containsa layer of an LC medium between two transparent electrodes, where the LCmedium usually has a negative dielectric anisotropy. In the switched-offstate, the molecules of the LC layer are aligned perpendicular to theelectrode surfaces (homeotropically) or have a tilted homeotropicalignment. On application of an electrical voltage to the twoelectrodes, a realignment of the LC molecules parallel to the electrodesurfaces takes place.

Furthermore, OCB (“optically compensated bend”) displays are known whichare based on a birefringence effect and have an LC layer with aso-called “bend” alignment and usually positive dielectric anisotropy.On application of an electrical voltage, a realignment of the LCmolecules perpendicular to the electrode surfaces takes place. Inaddition, OCB displays normally contain one or more birefringent opticalretardation films in order to prevent undesired transparency to light ofthe bend cell in the dark state. OCB displays have a broader viewingangle and shorter response times compared with TN displays.

Also known are so-called IPS (“in-plane switching”) displays, whichcontain an LC layer between two substrates, where the two electrodes arearranged on only one of the two substrates and preferably haveintermeshed, comb-shaped structures. On application of a voltage to theelectrodes, an electric field which has a significant component parallelto the LC layer is thereby generated between them. This causesrealignment of the LC molecules in the layer plane.

Furthermore, so-called FFS (“fringe-field switching”) displays have beenreported (see, inter alia, S. H. Jung et al., Jpn. J. Appl. Phys.,Volume 43, No. 3, 2004, 1028), which contain two electrodes on the samesubstrate, one of which structured in a comb-shaped manner and the otheris unstructured. A strong, so-called “fringe field” is therebygenerated, i.e. a strong electric field close to the edge of theelectrodes, and, throughout the cell, an electric field which has both astrong vertical component and also a strong horizontal component. FFSdisplays have a low viewing-angle dependence of the contrast. FFSdisplays usually contain an LC medium with positive dielectricanisotropy, and an alignment layer, usually of polyimide, which providesplanar alignment to the molecules of the LC medium.

FFS displays can be operated as active-matrix or passive-matrixdisplays. In the case of active-matrix displays, individual pixels areusually addressed by integrated, non-linear active elements, such as,for example, transistors (for example thin-film transistors (“TFTs”)),while in the case of passive-matrix displays, individual pixels areusually addressed by the multiplex method, as known from the prior art.

Furthermore, FFS displays have been disclosed (see S. H. Lee et al.,Appl. Phys. Lett. 73(20), 1998, 2882-2883 and S. H. Lee et al., LiquidCrystals 39(9), 2012, 1141-1148), which have similar electrode designand layer thickness as FFS displays, but comprise a layer of an LCmedium with negative dielectric anisotropy instead of an LC medium withpositive dielectric anisotropy. The LC medium with negative dielectricanisotropy shows a more favourable director orientation that has lesstilt and more twist orientation compared to the LC medium with positivedielectric anisotropy, as a result of which these displays have a highertransmission. The displays further comprise an alignment layer,preferably of polyimide provided on at least one of the substrates thatis in contact with the LC medium and induces planar alignment of the LCmolecules of the LC medium. These displays are also known as “UltraBrightness FFS (UB-FFS)” mode displays. These displays require an LCmedium with high reliability.

The term “reliability” as used hereinafter means the quality of theperformance of the display during time and with different stress loads,such as light load, temperature, humidity, voltage, and comprisesdisplay effects such as image sticking (area and line image sticking),mura, yogore etc. which are known to the skilled person in the field ofLC displays. As a standard parameter for categorising the reliabilityusually the voltage holding ration (VHR) value is used, which is ameasure for maintaining a constant electrical voltage in a test display.Among other factors, a high VHR is a prerequisite for a high reliabilityof the LC medium.

In VA displays of the more recent type, uniform alignment of the LCmolecules is restricted to a plurality of relatively small domainswithin the LC cell. Disclinations may exist between these domains, alsoknown as tilt domains. VA displays having tilt domains have, comparedwith conventional VA displays, a greater viewing-angle independence ofthe contrast and the grey shades. In addition, displays of this type aresimpler to produce since additional treatment of the electrode surfacefor uniform alignment of the molecules in the switched-on state, suchas, for example, by rubbing, is no longer necessary. Instead, thepreferential direction of the tilt or pretilt angle is controlled by aspecial design of the electrodes.

In so-called MVA (“multidomain vertical alignment”) displays, this isusually achieved by the electrodes having protrusions which cause alocal pretilt. As a consequence, the LC molecules are aligned parallelto the electrode surfaces in different directions in different, definedregions of the cell on application of a voltage. “Controlled” switchingis thereby achieved, and the formation of interfering disclination linesis prevented. Although this arrangement improves the viewing angle ofthe display, it results, however, in a reduction in its transparency tolight. A further development of MVA uses protrusions on only oneelectrode side, while the opposite electrode has slits, which improvesthe transparency to light. The slitted electrodes generate aninhomogeneous electric field in the LC cell on application of a voltage,meaning that controlled switching is still achieved. For furtherimprovement of the transparency to light, the separations between theslits and protrusions can be increased, but this in turn results in alengthening of the response times. In so-called PVA (“patterned VA”)displays, protrusions are rendered completely superfluous in that bothelectrodes are structured by means of slits on the opposite sides, whichresults in increased contrast and improved transparency to light, but istechnologically difficult and makes the display more sensitive tomechanical influences (“tapping”, etc.). For many applications, such as,for example, monitors and especially TV screens, however, a shorteningof the response times and an improvement in the contrast and luminance(transmission) of the display are demanded.

A further development are displays of the so-called PS (“polymersustained”) or PSA (“polymer sustained alignment”) type, for which theterm “polymer stabilised” is also occasionally used. In these, a smallamount (for example 0.3% by weight, typically <1% by weight) of one ormore polymerisable, compound(s), preferably polymerisable monomericcompound(s), is added to the LC medium and, after filling the LC mediuminto the display, is polymerised or crosslinked in situ, usually by UVphotopolymerisation, optionally while a voltage is applied to theelectrodes of the display. The polymerisation is carried out at atemperature where the LC medium exhibits a liquid crystal phase, usuallyat room temperature. The addition of polymerisable mesogenic orliquid-crystalline compounds, also known as reactive mesogens or “RMs”,to the LC mixture has proven particularly suitable.

Unless indicated otherwise, the term “PSA” is used hereinafter whenreferring to displays of the polymer sustained alignment type ingeneral, and the term “PS” is used when referring to specific displaymodes, like PS-VA, PS-TN and the like.

Also, unless indicated otherwise, the term “RM” is used hereinafter whenreferring to a polymerisable mesogenic or liquid-crystalline compound.

In the meantime, the PS(A) principle is being used in variousconventional LC display modes. Thus, for example, PS-VA, PS-OCB, PS-IPS,PS-FFS, PSUB-FFS and PS-TN displays are known. The polymerisation of theRMs preferably takes place with an applied voltage in the case of PS-VAand PS-OCB displays, and with or without, preferably without, an appliedvoltage in the case of PS-IPS displays. As can be demonstrated in testcells, the PS(A) method results in a pretilt in the cell. In the case ofPS-OCB displays, for example, it is possible for the bend structure tobe stabilised so that an offset voltage is unnecessary or can bereduced. In the case of PS-VA displays, the pretilt has a positiveeffect on response times. For PS-VA displays, a standard MVA or PVApixel and electrode layout can be used. In addition, however, it is alsopossible, for example, to manage with only one structured electrode sideand no protrusions, which significantly simplifies production and at thesame time results in very good contrast and in very good transparency tolight.

Furthermore, the so-called posi-VA displays (“positive VA”) have provento be a particularly suitable mode. Like in classical VA displays, theinitial orientation of the LC molecules in posi-VA displays ishomeotropic, i.e. substantially perpendicular to the substrates, in theinitial state when no voltage is applied. However, in contrast toclassical VA displays, in posi-VA displays LC media with positivedielectric anisotropy are used. Like in the usually used IPS displays,the two electrodes in posi-VA displays are arranged on only one of thetwo substrates, and preferably exhibit intermeshed and comb-shaped(interdigital) structures. By application of a voltage to theinterdigital electrodes, which create an electrical field that issubstantially parallel to the layer of the LC medium, the LC moleculesare transferred into an orientation that is substantially parallel tothe substrates.

In posi-VA displays polymer stabilisation, by addition of RMs to the LCmedium which are polymerised in the display, has also proven to beadvantageous, as a significant reduction of the switching times couldthereby be realised.

PS-VA displays are described, for example, in EP 1 170 626 A2, U.S. Pat.Nos. 6,861,107, 7,169,449, US 2004/0191428 A1, US 2006/0066793 A1 and US2006/0103804 A1. PS-OCB displays are described, for example, inT.-J-Chen et al., Jpn. J. Appl. Phys. 45, 2006, 2702-2704 and S. H. Kim,L.-C-Chien, Jpn. J. Appl. Phys. 43, 2004, 7643-7647. PS-IPS displays aredescribed, for example, in U.S. Pat. No. 6,177,972 and Appl. Phys. Lett.1999, 75(21), 3264. PS-TN displays are described, for example, in OpticsExpress 2004, 12(7), 1221.

Below the layer formed by the phase-separated and polymerised RMs whichinduce the above mentioned pretilt angle, the PSA display typicallycontains an alignment layer, for example of polyimide, that provides theinitial alignment of the LC molecules before the polymer stabilisationstep.

Rubbed polyimide layers have been used for a long time as alignmentlayers. However, the rubbing process causes a number of problems, likemura, contamination, problems with static discharge, debris, etc.Therefore instead of rubbed polyimide layers it was proposed to usepolyimide layers prepared by photoalignment, utilizing a light-inducedorientational ordering of the alignment surface. This can be achievedthrough photodecomposition, photodimerisation or photoisomerisation bymeans of polarised light.

However, still a suitably derivatised polyimide layer is required thatcomprises the photoreactive group. Generally the effort and costs forproduction of such a polyimide layer, treatment of the poylimide andimprovement with bumps or polymer layers are relatively great.

In addition, it was observed that unfavourable interaction of thepolyimide alignment layer with certain compounds of the LC medium oftenleads to a reduction of the electrical resistance of the display. Thenumber of suitable and available LC compounds is thus significantlyreduced, at the expense of display parameters like viewing-angledependence, contrast, and response times which are aimed to be improvedby the use of such LC compounds. It was therefore desired to omit thepolyimide alignment layers.

For some display modes this was achieved by adding a self alignmentagent or additive to the LC medium that induces the desired alignment,for example homeotropic or planar alignment, in situ by a selfassembling mechanism. Thereby the alignment layer can be omitted on oneor both of the substrates. These display modes are also known as“self-aligned” or “self-aligning” (SA) modes.

In SA displays a small amount, typically 0.1 to 2.5%, of a self-aligningadditive is added to the LC medium. Suitable self-aligning additives arefor example compounds having an organic core group and attached theretoone or more polar anchor groups, which are capable of interacting withthe substrate surface, causing the additives on the substrate surface toalign and induce the desired alignment also in the LC molecules.Preferred self-aligning additives comprise for example a mesogenic groupand a straight-chain or branched alkyl side chain that is terminatedwith one or more polar anchor groups, for example selected from hydroxy,carboxy, amino or thiol groups. The self-aligning additives may alsocontain one or more polymerisable groups that can be polymerised undersimilar conditions as the RMs used in the PSA process.

Hitherto SA-VA displays and SA-FFS displays haven been disclosed.Suitable self-aligning additives to induce homeotropic alignment,especially for use in SA-VA mode displays, are disclosed for example inUS 2013/0182202 A1, US 2014/0838581 A1, US 2015/0166890 A1 and US2015/0252265 A1.

The SA mode can also be used in combination with the PSA mode. An LCmedium for use in a display of such a combined mode thus contains bothone or more RMs and one or more self-aligning additives.

Like the conventional LC displays described above, PSA displays can beoperated as active-matrix or passive-matrix displays. In the case ofactive-matrix displays, individual pixels are usually addressed byintegrated, non-linear active elements, such as, for example,transistors (for example thin-film transistors (“TFTs”)), while in thecase of passive-matrix displays, individual pixels are usually addressedby the multiplex method, as known from the prior art.

The PSA display may also comprise an alignment layer on one or both ofthe substrates forming the display cell. The alignment layer is usuallyapplied on the electrodes (where such electrodes are present) such thatit is in contact with the LC medium and induces initial alignment of theLC molecules. The alignment layer may comprise or consist of, forexample, a polyimide, which may also be rubbed, or may be prepared by aphotoalignment method.

In particular for monitor and especially TV applications, optimisationof the response times, but also of the contrast and luminance (thus alsotransmission) of the LC display continues to be demanded. The PSA methodcan provide significant advantages here. In particular in the case ofPS-VA, PS-IPS, PS-FFS and PS-posi-VA displays, a shortening of theresponse times, which correlate with a measurable pretilt in test cells,can be achieved without significant adverse effects on other parameters.

Prior art has suggested biphenyl diacrylates or dimethacrylates, whichare optionally fluorinated as RMs for use in PSA displays

However, the problem arises that not all combinations consisting of anLC mixture and one or more RMs are suitable for use in PSA displaysbecause, for example, an inadequate tilt or none at all becomesestablished or since, for example, the VHR is inadequate for TFT displayapplications. In addition, it has been found that, on use in PSAdisplays, the LC mixtures and RMs known from the prior art do still havesome disadvantages. Thus, not every known RM which is soluble in LCmixtures is suitable for use in PSA displays. In addition, it is oftendifficult to find a suitable selection criterion for the RM besidesdirect measurement of the pretilt in the PSA display. The choice ofsuitable RMs becomes even smaller if polymerisation by means of UV lightwithout the addition of photoinitiators is desired, which may beadvantageous for certain applications.

In addition, the selected combination of LC host mixture/RM should havethe lowest possible rotational viscosity and the best possibleelectrical properties. In particular, it should have the highestpossible VHR. In PSA displays, a high VHR after irradiation with UVlight is particularly necessary since UV exposure is a requisite part ofthe display production process, but also occurs as normal exposureduring operation of the finished display.

In particular, it would be desirable to have available novel materialsfor PSA displays which produce a particularly small pretilt angle.Preferred materials here are those which produce a lower pretilt angleduring polymerisation for the same exposure time than the materialsknown to date, and/or through the use of which the (higher) pretiltangle that can be achieved with known materials can already be achievedafter a shorter exposure time. The production time (“tact time”) of thedisplay could thus be shortened and the costs of the production processreduced.

A further problem in the production of PSA displays is the presence orremoval of residual amounts of unpolymerised RMs, in particular afterthe polymerisation step for production of the pretilt angle in thedisplay. For example, unreacted RMs of this type may adversely affectthe properties of the display by, for example, polymerising in anuncontrolled manner during operation after finishing of the display.

Thus, the PSA displays known from the prior art often exhibit theundesired effect of so-called “image sticking” or “image burn”, i.e. theimage produced in the LC display by temporary addressing of individualpixels still remains visible even after the electric field in thesepixels has been switched off or after other pixels have been addressed.

This “image sticking” can occur on the one hand if LC host mixtureshaving a low VHR are used. The UV component of daylight or thebacklighting can cause undesired decomposition reactions of the LCmolecules therein and thus initiate the production of ionic orfree-radical impurities. These may accumulate, in particular, at theelectrodes or the alignment layers, where they may reduce the effectiveapplied voltage. This effect can also be observed in conventional LCdisplays without a polymer component.

In addition, an additional “image sticking” effect caused by thepresence of unpolymerised RMs is often observed in PSA displays.Uncontrolled polymerisation of the residual RMs is initiated here by UVlight from the environment or by the backlighting. In the switcheddisplay areas, this changes the tilt angle after a number of addressingcycles. As a result, a change in transmission in the switched areas mayoccur, while it remains unchanged in the unswitched areas.

It is therefore desirable for the polymerisation of the RMs to proceedas completely as possible during production of the PSA display and forthe presence of unpolymerised RMs in the display to be excluded as faras possible or reduced to a minimum. Thus, RMs and LC mixtures arerequired which enable or support highly effective and completepolymerisation of the RMs. In addition, controlled reaction of theresidual RM amounts would be desirable. This would be simpler if the RMpolymerised more rapidly and effectively than the compounds known todate.

A further problem that has been observed in the operation of PSAdisplays is the stability of the pretilt angle. Thus, it was observedthat the pretilt angle, which was generated during display manufactureby polymerising the RM as described above, does not remain constant butcan deteriorate after the display was subjected to voltage stress duringits operation. This can negatively affect the display performance, e.g.by increasing the black state transmission and hence lowering thecontrast.

Another problem to be solved is that the RMs of prior art do often havehigh melting points, and do only show limited solubility in manycurrently common LC mixtures, and therefore frequently tend tospontaneously crystallise out of the mixture. In addition, the risk ofspontaneous polymerisation prevents the LC host mixture being warmed inorder to dissolve the polymerisable component, meaning that the bestpossible solubility even at room temperature is necessary. In addition,there is a risk of separation, for example on introduction of the LCmedium into the LC display (chromatography effect), which may greatlyimpair the homogeneity of the display. This is further increased by thefact that the LC media are usually introduced at low temperatures inorder to reduce the risk of spontaneous polymerisation (see above),which in turn has an adverse effect on the solubility.

Another problem observed in prior art is that the use of conventional LCmedia in LC displays, including but not limited to displays of the PSAtype, often leads to the occurrence of mura in the display, especiallywhen the LC medium is filled in the display cell manufactured using theone drop filling (ODF) method. This phenomenon is also known as “ODFmura”. It is therefore desirable to provide LC media which lead toreduced ODF mura.

Another problem observed in prior art is that LC media for use in PSAdisplays, including but not limited to displays of the PSA type, dooften exhibit high viscosities and, as a consequence, high switchingtimes. In order to reduce the viscosity and switching time of the LCmedium, it has been suggested in prior art to add LC compounds with analkenyl group. However, it was observed that LC media containing alkenylcompounds often show a decrease of the reliability and stability, and adecrease of the VHR especially after exposure to UV radiation.Especially for use in PSA displays this is a considerable disadvantage,because the photo-polymerisation of the RMs in the PSA display isusually carried out by exposure to UV radiation, which may cause a VHRdrop in the LC medium.

There is thus still a great demand for PSA displays and LC media andpolymerisable compounds for use in such displays, which do not show thedrawbacks as described above, or only do so to a small extent, and haveimproved properties.

In particular, there is a great demand for PSA displays, and LC mediaand polymerisable compounds for use in such PSA displays, which enable ahigh specific resistance at the same time as a large working-temperaturerange, short response times, even at low temperatures, and a lowthreshold voltage, a low pretilt angle, a multiplicity of grey shades,high contrast and a broad viewing angle, have high reliability and highvalues for the VHR after UV exposure, and, in case of the polymerisablecompounds, have low melting points and a high solubility in the LC hostmixtures. In PSA displays for mobile applications, it is especiallydesired to have available LC media that show low threshold voltage andhigh birefringence.

In prior art several types of RMs have been reported for use in PSAdisplays, for example RMs having a biphenyl or terphenyl mesogenic coreand attached thereto two or three polymerisable acrylate or methacrylategroups. Biphenyl RMs were shown to exhibit limited polymerisation speedbut good reliability parameters, like high VHR or tilt stability, whileterphenyl RMs were shown to exhibit fast polymerisation speed butlimited reliability parameters. It is therefore desirable to haveavailable RMs that exhibit both fast polymerisation speed and goodreliability parameters.

The invention is based on the object of providing novel suitablematerials, in particular RMs and LC media comprising the same, for usein PSA displays, which do not have the disadvantages indicated above ordo so to a reduced extent.

In particular, the invention is based on the object of providing RMs,and LC media comprising them, for use in PSA displays, which enable veryhigh specific resistance values, high VHR values, high reliability, lowthreshold voltages, short response times, high birefringence, show goodUV absorption especially at longer wavelengths, enable quick andcomplete polymerisation of the RMs, allow the generation of a lowpretilt angle, preferably as quickly as possible, enable a highstability of the pretilt even after longer time and/or after UVexposure, reduce or prevent the occurrence of “image sticking” and “ODFmura” in the display, and in case of the RMs polymerise as rapidly andcompletely as possible and show a high solubility in the LC media whichare typically used as host mixtures in PSA displays.

A further object of the invention is to provide RMs for use in PSAdisplays which exhibit both fast polymerisation speed and goodreliability parameters, like high VHR or tilt stability.

A further object of the invention is the provision of novel RMs, inparticular for optical, electro-optical and electronic applications, andof suitable processes and intermediates for the preparation thereof.

These objects have been achieved in accordance with the presentinvention by materials and processes as described in the presentapplication. In particular, it has been found, surprisingly, that theuse of RMs of formula I as described hereinafter allows achieving theadvantageous effects as mentioned above. These compounds arecharacterized in that they contain a mesogenic core with one or morebenzene or naphthalene rings, one or more polymerisable reactive groupsattached thereto, and one or more methoxymethyl substituents attachedthereto.

It was surprisingly found that the use of these RMs, and of LC mediacomprising them, in PSA displays facilitates a quick and completeUV-photopolymerisation reaction in particular at longer UV wavelengthsin the range from 300-380 nm and especially above 320 nm, even withoutthe addition of photoinitiator, leads to a fast generation of a largeand stable pretilt angle, reduces image sticking and ODF mura in thedisplay, leads to a high reliability and a high VHR value after UVphotopolymerisation, especially in case of LC host mixtures containingLC compounds with an alkenyl group, and enables to achieve fast responsetimes, a low threshold voltage and a high birefringence.

In addition, the RMs according to the invention have low melting points,good solubility in a wide range of LC media, especially in commerciallyavailable LC host mixtures for PSA use, and a low tendency tocrystallisation. Besides, they show good absorption at longer UVwavelengths, in particular in the range from 300-380 nm, and enable aquick and complete polymerisation with small amounts of residual,unreacted RMs in the cell.

Also, it was surprisingly found that the RMs according to the presentinvention combine a fast polymerisation speed, which is similar to thatof terphenyl RMs, with good reliability parameters similar to biphenylRMs. This results in a superior overall performance compared to RMs ofthe state of the art.

WO 2014/142168 A1 discloses an LC aligning agent containingcrosslinkable compounds with a photoreactive group, and explicitlydiscloses the following compound

However, this document does neither disclose nor suggest RMs asdisclosed and claimed hereinafter, or their use in PSA displays and theadvantages thereby achieved.

SUMMARY OF THE INVENTION

The invention relates to compounds of formula IP-Sp-A¹-(Z¹-A²)_(z)-R  Iwherein the individual radicals, independently of each other and on eachoccurrence identically or differently, have the following meanings

-   P a polymerisable group,-   Sp a spacer group or a single bond,-   A¹, A² benzene or naphthalene, which are optionally substituted by    one or more groups L, L¹¹ or P-Sp-,-   Z¹ —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —OCH₂—, —CH₂O—, —SCH₂—,    —CH₂S—, —CF₂O—, —OCF₂—, —CF₂S—, —SCF₂—, —(CH₂)_(n1)—, —CF₂CH₂—,    —CH₂CF₂—, —(CF₂)_(n1)—, —CH═CH—, —CF═CF—, —CH═CF—, —CF═CH—, —C≡C—,    —CH═CH—CO—O—, —O—CO—CH═CH—, —CH₂—CH₂—CO—O—, —O—CO—CH₂—CH₂—,    —CR⁰R⁰⁰—, or a single bond,-   R¹, R⁰⁰ H or alkyl having 1 to 12 C atoms,-   R H, L, L¹¹ or P-Sp-,-   L¹¹ —CH₂—O—CH₃,-   L F, Cl, —CN, P-Sp- or straight chain, branched or cyclic alkyl    having 1 to 25 C atoms, wherein one or more non-adjacent CH₂-groups    are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—    in such a manner that O- and/or S-atoms are not directly connected    with each other, and wherein one or more H atoms are each optionally    replaced by P-Sp-, F or Cl,-   z 0, 1, 2 or 3,-   n1 1, 2, 3 or 4,    characterized in that the compounds contain at least one group A¹ or    A² that is substituted by at least one substituent L¹¹,    with the proviso that, in case A¹-(Z¹-A²)_(z) denotes biphenyl and    the compound contains two or more groups P-Sp-, then at least one of    the groups Sp that are present in the compound is a single bond.

The invention further relates to the use of compounds of formula I aspolymerisable compounds in LC media and LC displays, especially in theLC medium, active layer or alignment layer of an LC display, wherein theLC displays are preferably PSA displays.

The invention further relates to methods for preparing compounds offormula I, and to novel intermediates used or obtained in these methods.

The invention furthermore relates to an LC medium comprising one or morecompounds of formula I.

The invention furthermore relates to an LC medium comprising one or morepolymerisable compounds, at least one of which is a compound of formulaI.

The invention furthermore relates to an LC medium comprising

-   -   a polymerisable component A) comprising, preferably consisting        of, one or more polymerisable compounds, at least one of which        is a compound of formula I, and    -   a liquid-crystalline component B), hereinafter also referred to        as “LC host mixture”, comprising, preferably consisting of, one        or more mesogenic or liquid-crystalline compounds.

The liquid-crystalline component B) of an LC medium according to thepresent invention is hereinafter also referred to as “LC host mixture”,and preferably comprises one or more, preferably at least two mesogenicor LC compounds selected from low-molecular-weight compounds which areunpolymerisable.

The invention furthermore relates to an LC medium as described above andbelow, wherein the LC host mixture or component B) comprises at leastone mesogenic or LC compound comprising an alkenyl group.

The invention furthermore relates to an LC medium or LC display asdescribed above, wherein the compounds of formula I, or thepolymerisable compounds of component A), are polymerised.

The invention furthermore relates to a process for preparing an LCmedium as described above and below, comprising the steps of mixing oneor more mesogenic or LC compounds, or an LC host mixture or LC componentB) as described above and below, with one or more compounds of formulaI, and optionally with further LC compounds and/or additives.

The invention furthermore relates to the use of compounds of formula Iand LC media according to the invention in PSA displays, in particularthe use in PSA displays containing an LC medium, for the production of atilt angle in the LC medium by in-situ polymerisation of the compound(s)of the formula I in the PSA display, preferably in an electric ormagnetic field.

The invention furthermore relates to an LC display comprising one ormore compounds of formula I or an LC medium according to the invention,in particular a PSA display, particularly preferably a PS-VA, PS-OCB,PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA or PS-TN display.

The invention furthermore relates to the use of compounds of formula Iand LC media according to the invention in polymer stabilised SA-VA andSA-FFS displays, and to a polymer stabilised SA-VA or SA-FFS displaycomprising one or more compounds of formula I or an LC medium accordingto the invention.

The invention furthermore relates to an LC display comprising a polymerobtainable by polymerisation of one or more compounds of formula I or ofa polymerisable component A) as described above, or comprising an LCmedium according to the invention, which is preferably a PSA display,very preferably a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA,PS-TN, or polymer stabilised SA-VA or SA-FFS display.

The invention furthermore relates to an LC display of the PSA typecomprising two substrates, at least one which is transparent to light,an electrode provided on each substrate or two electrodes provided ononly one of the substrates, and located between the substrates a layerof an LC medium that comprises one or more polymerisable compounds andan LC component as described above and below, wherein the polymerisablecompounds are polymerised between the substrates of the display.

The invention furthermore relates to a process for manufacturing an LCdisplay as described above and below, comprising the steps of filling orotherwise providing an LC medium, which comprises one or morepolymerisable compounds as described above and below, between thesubstrates of the display, and polymerising the polymerisable compounds.

The PSA displays according to the invention have two electrodes,preferably in the form of transparent layers, which are applied to oneor both of the substrates. In some displays, for example in PS-VA,PS-OCB, PS-TN or polymer stabilised SA-VA displays, one electrode isapplied to each of the two substrates. In other displays, for example inPS-posi-VA, PS-IPS or PS-FFS, PS-UB-FFS or polymer stabilised SA-FFSdisplays, both electrodes are applied to only one of the two substrates.

In a preferred embodiment the polymerisable component is polymerised inthe LC display while a voltage is applied to the electrodes of thedisplay.

The polymerisable compounds of the polymerisable component arepreferably polymerised by photopolymerisation, very preferably by UVphotopolymerisation.

Prior art document WO 2014/142168 A1 discloses an LC aligning agent thatis crosslinkable and photoreactive and contains benzyloxymethyl groupswhich are designated as crosslinkable groups. However in order to starta crosslinking reaction of such benzyloxymethyl groups the presence of astrong acid is required, in analogy to phenol formaldehyde resins. Suchbenzyloxymethyl groups do however not react under the polymerisationconditions as used for the compounds of formula I according to thepresent invention. Thus the CH₂OCH₃ group in this application is notconsidered to be within the meaning of the term “polymerisable group” asused herein.

The conditions for the polymerisation of compounds of formula I arepreferably selected such that the CH₂OCH₃ substituents do notparticipate in the polymerisation reaction. Preferably the LC mediadisclosed and claimed in the present application do not contain aphotoacid or another additive that enables participation of the CH₂OCH₃group in a crosslinking reaction.

The invention furthermore relates to compounds of formula IIPg-Sp-A¹-(Z¹-A²)_(z)-R*  II

Wherein Pg denotes OH, a protected hydroxyl group or a masked hydroxylgroup, R* denotes R or Pg-Sp-, and Sp, A¹, A², R, Z and z have themeanings given in formula I or one of the preferred meanings given aboveand below.

The invention furthermore relates to the use of compounds of formula IIas intermediates in the synthesis of polymerisable compounds, especiallythose of formula I.

The invention furthermore relates to a process for synthesizingcompounds of formula I by esterification or etherification of thecompounds of formula II, wherein Pg denotes OH, using correspondingacids, acid derivatives, or halogenated compounds containing apolymerisable group P.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of formula I show the following advantageous propertieswhen used in PSA displays:

-   -   a suitable tilt generation which is inside a certain process        window,    -   fast polymerization leading to minimal residues of RM after the        UV-process,    -   a high voltage-holding-ratio after the UV-process,    -   good tilt stability,    -   sufficient stability against heat,    -   sufficient solubility in organic solvents typically used in        display manufacture.

In particular the compounds of formula I combine a fast polymerisationspeed which is similar to terphenyl RMs with good reliability parameterssimilar to biphenyl RMs. This results in a superior overall performanceof the compounds compared to RMs of the state of the art when used inPSA displays.

In the compounds of formula I the presence of one or moremethoxymethylene substituents L¹¹ on the benzene or naphthylene ringswere found to enhance superior properties of the compounds, like fastpolymerisation speed and good reliability. However, the substituents L¹¹are not designated as a polymerisable or crosslinkable group that shouldparticipate in the polymerisation reaction of the compound.

A preferred embodiment of the present invention thus relates to the useof the compounds of formula I in a polymerisation reaction where theconditions for polymerisation of the groups P are selected such that themethoxymethylene substituents, or groups L¹¹, do not participate in thepolymerisation reaction.

Unless stated otherwise, the compounds of formula I are preferablyselected from achiral compounds.

As used herein, the terms “active layer” and “switchable layer” mean alayer in an electrooptical display, for example an LC display, thatcomprises one or more molecules having structural and opticalanisotropy, like for example LC molecules, which change theirorientation upon an external stimulus like an electric or magneticfield, resulting in a change of the transmission of the layer forpolarized or unpolarized light.

As used herein, the terms “tilt” and “tilt angle” will be understood tomean a tilted alignment of the LC molecules of an LC medium relative tothe surfaces of the cell in an LC display (here preferably a PSAdisplay). The tilt angle here denotes the average angle (<90°) betweenthe longitudinal molecular axes of the LC molecules (LC director) andthe surface of the plane-parallel outer plates which form the LC cell. Alow value for the tilt angle (i.e. a large deviation from the 90° angle)corresponds to a large tilt here. A suitable method for measurement ofthe tilt angle is given in the examples. Unless indicated otherwise,tilt angle values disclosed above and below relate to this measurementmethod.

As used herein, the terms “reactive mesogen” and “RM” will be understoodto mean a compound containing a mesogenic or liquid crystallineskeleton, and one or more functional groups attached thereto which aresuitable for polymerisation and are also referred to as “polymerisablegroup” or “P”.

Unless stated otherwise, the term “polymerisable compound” as usedherein will be understood to mean a polymerisable monomeric compound.

An SA-VA or SA-FFS according to the present invention will be of thepolymer stabilised mode as it contains, or is manufactured by use of, anLC medium containing an RM of formula I. Consequently as used herein,the terms “SA-VA display” and “SA-FFS display”, when referring to adisplay according to the present invention, will be understood to referto a polymer stabilised SA-VA or SA-FFS display even if not explicitlymentioned.

As used herein, the term “low-molecular-weight compound” will beunderstood to mean to a compound that is monomeric and/or is notprepared by a polymerisation reaction, as opposed to a “polymericcompound” or a “polymer”.

As used herein, the term “unpolymerisable compound” will be understoodto mean a compound that does not contain a functional group that issuitable for polymerisation under the conditions usually applied for thepolymerisation of the RMs.

The term “mesogenic group” as used herein is known to the person skilledin the art and described in the literature, and means a group which, dueto the anisotropy of its attracting and repelling interactions,essentially contributes to causing a liquid-crystal (LC) phase inlow-molecular-weight or polymeric substances. Compounds containingmesogenic groups (mesogenic compounds) do not necessarily have to havean LC phase themselves. It is also possible for mesogenic compounds toexhibit LC phase behaviour only after mixing with other compounds and/orafter polymerisation. Typical mesogenic groups are, for example, rigidrod- or disc-shaped units. An overview of the terms and definitions usedin connection with mesogenic or LC compounds is given in Pure Appl.Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew.Chem. 2004, 116, 6340-6368.

The term “spacer group”, hereinafter also referred to as “Sp”, as usedherein is known to the person skilled in the art and is described in theliterature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C.Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. Asused herein, the terms “spacer group” or “spacer” mean a flexible group,for example an alkylene group, which connects the mesogenic group andthe polymerisable group(s) in a polymerisable mesogenic compound.

Above and below,

denotes a trans-1,4-cyclohexylene ring, and

denotes a 1,4-phenylene ring.

In a group

the single bond shown between the two ring atoms can be attached to anyfree position of the benzene ring.

Above and below “organic group” denotes a carbon or hydrocarbon group.

“Carbon group” denotes a mono- or polyvalent organic group containing atleast one carbon atom, where this either contains no further atoms (suchas, for example, —C≡C—) or optionally contains one or more furtheratoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge (forexample carbonyl, etc.). The term “hydrocarbon group” denotes a carbongroup which additionally contains one or more H atoms and optionally oneor more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Teor Ge.

“Halogen” denotes F, Cl, Br or I, preferably F or Cl.

—CO—, —C(═O)— and —C(O)— denote a carbonyl group, i.e.

A carbon or hydrocarbon group can be a saturated or unsaturated group.Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. Acarbon or hydrocarbon radical having more than 3 C atoms can bestraight-chain, branched and/or cyclic and may also contain spiro linksor condensed rings.

The terms “alkyl”, “aryl”, “heteroaryl”, etc., also encompass polyvalentgroups, for example alkylene, arylene, heteroarylene, etc.

The term “aryl” denotes an aromatic carbon group or a group derivedtherefrom. The term “heteroaryl” denotes “aryl” as defined above,containing one or more heteroatoms, preferably selected from N, O, S,Se, Te, Si and Ge.

Preferred carbon and hydrocarbon groups are optionally substituted,straight-chain, branched or cyclic, alkyl, alkenyl, alkynyl, alkoxy,alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxyhaving 1 to 40, preferably 1 to 20, very preferably 1 to 12, C atoms,optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to25, C atoms, or optionally substituted alkylaryl, arylalkyl,alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl,arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to25, C atoms, wherein one or more C atoms may also be replaced by heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.

Further preferred carbon and hydrocarbon groups are C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, C₃-C₂₀ allyl, C₄-C₂₀ alkylidenyl, C₄-C₂₀polyenyl, C₆-C₂₀ cycloalkyl, C₄-C₁₅ cycloalkenyl, C₆-C₃₀ aryl, C₆-C₃₀alkylaryl, C₆-C₃₀ arylalkyl, C₆-C₃₀ alkylaryloxy, C₆-C₃₀ arylalkyloxy,C₂-C₃₀ heteroaryl, C₂-C₃₀ heteroaryloxy.

Particular preference is given to C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂alkynyl, C₆-C₂₅ aryl and C₂-C₂₅ heteroaryl.

Further preferred carbon and hydrocarbon groups are straight-chain,branched or cyclic alkyl having 1 to 20, preferably 1 to 12, C atoms,which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I orCN and in which one or more non-adjacent CH₂ groups may each bereplaced, independently of one another, by —C(R^(x))═C(R^(x))—, —C≡C—,—N(R^(x))—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way thatO and/or S atoms are not linked directly to one another.

R^(x) preferably denotes H, F, Cl, CN, a straight-chain, branched orcyclic alkyl chain having 1 to 25 C atoms, in which, in addition, one ormore non-adjacent C atoms may be replaced by —O—, —S—, —CO—, —CO—O—,—O—CO—, —O—CO—O— and in which one or more H atoms may be replaced by For Cl, or denotes an optionally substituted aryl or aryloxy group with 6to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxygroup with 2 to 30 C atoms.

Preferred alkyl groups are, for example, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl,s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl,cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl,n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl,2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.

Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl,pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl,octenyl, cyclooctenyl, etc.

Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl,pentynyl, hexynyl, octynyl, etc.

Preferred alkoxy groups are, for example, methoxy, ethoxy,2-methoxyethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy,t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy,n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, etc.

Preferred amino groups are, for example, dimethylamino, methylamino,methylphenylamino, phenylamino, etc.

Aryl and heteroaryl groups can be monocyclic or polycyclic, i.e. theycan contain one ring (such as, for example, phenyl) or two or morerings, which may also be fused (such as, for example, naphthyl) orcovalently bonded (such as, for example, biphenyl), or contain acombination of fused and linked rings. Heteroaryl groups contain one ormore heteroatoms, preferably selected from O, N, S and Se.

Particular preference is given to mono-, bi- or tricyclic aryl groupshaving 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl groupshaving 5 to 25 ring atoms, which optionally contain fused rings and areoptionally substituted. Preference is furthermore given to 5-, 6- or7-membered aryl and heteroaryl groups, in which, in addition, one ormore CH groups may be replaced by N, S or O in such a way that O atomsand/or S atoms are not linked directly to one another.

Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl,[1,1′:3′,1″]terphenyl-2′-yl, naphthyl, anthracene, binaphthyl,phenanthrene, 9,10-dihydro-phenanthrene, pyrene, dihydropyrene,chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene,indenofluorene, spirobifluorene, etc.

Preferred heteroaryl groups are, for example, 5-membered rings, such aspyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole,furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole,1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole,1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole,1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings, such aspyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine,1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine,1,2,3,5-tetrazine, or condensed groups, such as indole, isoindole,indolizine, indazole, benzimidazole, benzotriazole, purine,naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole,quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole,phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran,dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline,benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine,phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine,quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline,phenanthridine, phenanthroline, thieno[2,3b]thiophene,thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene,dibenzothiophene, benzothiophene, benzothiadiazothiophene, orcombinations of these groups.

The aryl and heteroaryl groups mentioned above and below may also besubstituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl orfurther aryl or heteroaryl groups.

The (non-aromatic) alicyclic and heterocyclic groups encompass bothsaturated rings, i.e. those containing exclusively single bonds, andalso partially unsaturated rings, i.e. those which may also containmultiple bonds. Heterocyclic rings contain one or more heteroatoms,preferably selected from Si, O, N, S and Se.

The (non-aromatic) alicyclic and heterocyclic groups can be monocyclic,i.e. contain only one ring (such as, for example, cyclohexane), orpolycyclic, i.e. contain a plurality of rings (such as, for example,decahydronaphthalene or bicyclooctane). Particular preference is givento saturated groups. Preference is furthermore given to mono-, bi- ortricyclic groups having 5 to 25 ring atoms, which optionally containfused rings and are optionally substituted. Preference is furthermoregiven to 5-, 6-, 7- or 8-membered carbocyclic groups, in which, inaddition, one or more C atoms may be replaced by Si and/or one or moreCH groups may be replaced by N and/or one or more non-adjacent CH₂groups may be replaced by —O— and/or —S—.

Preferred alicyclic and heterocyclic groups are, for example, 5-memberedgroups, such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran,pyrrolidine, 6-membered groups, such as cyclohexane, silinane,cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane,1,3-dithiane, piperidine, 7-membered groups, such as cycloheptane, andfused groups, such as tetrahydronaphthalene, decahydronaphthalene,indane, bicyclo[1.1.1]-pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl,spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindane-2,5-diyl.

Preferred substituents are, for example, solubility-promoting groups,such as alkyl or alkoxy, electron-withdrawing groups, such as fluorine,nitro or nitrile, or substituents for increasing the glass transitiontemperature (Tg) in the polymer, in particular bulky groups, such as,for example, t-butyl or optionally substituted aryl groups.

Preferred substituents, hereinafter also referred to as “L^(S)”, are,for example, F, Cl, Br, I, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN,—C(═O)N(R^(x))₂, —C(═O)Y¹, —C(═O)R^(x), —N(R^(x))₂, straight-chain orbranched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxyor alkoxycarbonyloxy each having 1 to 25 C atoms, in which one or more Hatoms may optionally be replaced by F or Cl, optionally substitutedsilyl having 1 to 20 Si atoms, or optionally substituted aryl having 6to 25, preferably 6 to 15, C atoms,

wherein R^(x) denotes H, F, Cl, CN, or straight chain, branched orcyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacentCH₂-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—,—O—CO—O— in such a manner that O- and/or S-atoms are not directlyconnected with each other, and wherein one or more H atoms are eachoptionally replaced by F, Cl, P— or P-Sp-, andY¹ denotes halogen.

“Substituted silyl or aryl” preferably means substituted by halogen,—CN, R⁰, —OR⁰, —CO—R⁰, —CO—O—R⁰, —O—CO—R⁰ or —O—CO—O—R⁰, wherein R⁰denotes H or alkyl with 1 to 20 C atoms.

Particularly preferred substituents L^(S) are, for example, F, Cl, CN,NO₂, CH₃, C₂H₅, OCH₃, OC₂H₅, COCH₃, COC₂H₅, COOCH₃, COOC₂H₅, CF₃, OCF₃,OCHF₂, OC₂F₅, furthermore phenyl.

is preferably

in which L has one of the meanings indicated above.

The polymerisable group P is a group which is suitable for apolymerisation reaction, such as, for example, free-radical or ionicchain polymerisation, polyaddition or polycondensation, or for apolymer-analogous reaction, for example addition or condensation onto amain polymer chain. Particular preference is given to groups for chainpolymerisation, in particular those containing a C═C double bond or—C≡C— triple bond, and groups which are suitable for polymerisation withring opening, such as, for example, oxetane or epoxide groups.

Preferred groups P are selected from the group consisting ofCH₂═CW¹—CO—O—, CH₂═CW¹—CO—,

CH₂═CW²—(O)_(k3)—, CW¹═CH—CO—(O)_(k3)—, CW¹═CH—CO—NH—, CH₂═CW¹—CO—NH—,CH₃—CH═CH—O—, (CH₂═CH)₂CH—OCO—, (CH₂═CH—CH₂)₂CH—OCO—, (CH₂═CH)₂CH—O—,(CH₂═CH—CH₂)₂N—, (CH₂═CH—CH₂)₂N—CO—, HO—CW²W³—, HS—CW²W³—, HW²N,HO—CW²W³—NH—, CH₂═CW¹—CO—NH—, CH₂═CH—(COO)_(k1)-Phe-(O)_(k2)—,CH₂═CH—(CO)_(k1)-Phe-(O)_(k2)—, Phe-CH═CH—, HOOC—, OCN— and W⁴W⁵W⁶Si—,in which W¹ denotes H, F, Cl, CN, CF₃, phenyl or alkyl having 1 to 5 Catoms, in particular H, F, Cl or CH₃, W² and W³ each, independently ofone another, denote H or alkyl having 1 to 5 C atoms, in particular H,methyl, ethyl or n-propyl, W⁴, W⁵ and W⁶ each, independently of oneanother, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms,W⁷ and W⁸ each, independently of one another, denote H, Cl or alkylhaving 1 to 5 C atoms, Phe denotes 1,4-phenylene, which is optionallysubstituted by one or more radicals L as defined above which are otherthan P-Sp-, k₁, k₂ and k₃ each, independently of one another, denote 0or 1, k₃ preferably denotes 1, and k₄ denotes an integer from 1 to 10.

Very preferred groups P are selected from the group consisting ofCH₂═CW¹—CO—O—, CH₂═CW¹—CO—,

CH₂═CW²—O—, CH₂═CW²—, CW¹═CH—CO—(O)_(k3)—, CW¹═CH—CO—NH—,CH₂═CW¹—CO—NH—, (CH₂═CH)₂CH—OCO—, (CH₂═CH—CH₂)₂CH—OCO—, (CH₂═CH)₂CH—O—,(CH₂═CH—CH₂)₂N—, (CH₂═CH—CH₂)₂N—CO—, CH₂═CW¹—CO—NH—,CH₂═CH—(COO)_(k1)-Phe-(O)_(k2)—, CH₂═CH—(CO)_(k1)-Phe-(O)_(k2)—,Phe-CH═CH— and W⁴W⁵W⁶Si—, in which W¹ denotes H, F, Cl, CN, CF₃, phenylor alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH₃, W² and W³each, independently of one another, denote H or alkyl having 1 to 5 Catoms, in particular H, methyl, ethyl or n-propyl, W⁴, W⁵ and W⁶ each,independently of one another, denote CI, oxaalkyl or oxacarbonylalkylhaving 1 to 5 C atoms, W⁷ and W⁸ each, independently of one another,denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene,k₁, k₂ and k₃ each, independently of one another, denote 0 or 1, k₃preferably denotes 1, and k₄ denotes an integer from 1 to 10.

Very particularly preferred groups P are selected from the groupconsisting of CH₂═CW¹—CO—O—, in particular CH₂═CH—CO—O—,CH₂═C(CH₃)—CO—O— and CH₂═CF—CO—O—, furthermore CH₂═CH—O—,(CH₂═CH)₂CH—O—CO—, (CH₂═CH)₂CH—O—,

Further preferred polymerisable groups P are selected from the groupconsisting of vinyloxy, acrylate, methacrylate, fluoroacrylate,chloroacrylate, oxetane and epoxide, most preferably from acrylate andmethacrylate.

If the spacer group Sp is different from a single bond, it is preferablyof the formula Sp″—X″, so that the respective radical P-Sp- conforms tothe formula P-Sp″—X″-, wherein

-   Sp″ denotes linear or branched alkylene having 1 to 20, preferably 1    to 12, C atoms, which is optionally mono- or polysubstituted by F,    Cl, Br, I or CN and in which, in addition, one or more non-adjacent    CH₂ groups may each be replaced, independently of one another, by    —O—, —S—, —NH—, —N(R⁰)—, —Si(R⁰R⁰⁰—, —CO—, —CO—O—, —O—CO—, —O—CO—O—,    —S—CO—, —CO—S—, —N(R⁰⁰)—CO—O—, —O—CO—N(R⁰)—, —N(R⁰)—CO—N(R⁰⁰)—,    —CH═CH— or —C≡C— in such a way that O and/or S atoms are not linked    directly to one another,-   X″ denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—OC—O—, —CO—N(R⁰)—,    —N(R⁰)—CO—, —N(R⁰)—CO—N(R⁰⁰)—, —OCH₂—, —CH₂O—, —SCH₂—, —CH₂S—,    —CF₂O—, —OCF₂—, —CF₂S—, —SCF₂—, —CF₂CH₂—, —CH₂CF₂—, —CF₂CF₂—,    —CH═N—, —N═CH—, —N═N—, —CH═CR⁰—, —CY²═CY³—, —C≡C—, —CH═CH—CO—O—,    —O—OC—CH═CH— or a single bond,-   R⁰ and R⁰⁰ each, independently of one another, denote H or alkyl    having 1 to 20 C atoms, and-   Y² and Y³ each, independently of one another, denote H, F, Cl or CN.

X″ is preferably —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR⁰—,—NR⁰—CO—, —NR⁰—CO—NR⁰⁰— or a single bond.

Typical spacer groups Sp and -Sp″—X″— are, for example, —(CH₂)_(p1)—,—(CH₂)_(p1)—O—, —(CH₂)_(p1)—O—CO—, —(CH₂)_(p1)—CO—O—,—(CH₂)_(p1)—O—OC—O—, —(CH₂CH₂O)_(q1)—CH₂CH₂—, —CH₂CH₂—S—CH₂CH₂—,—CH₂CH₂—NH—CH₂CH₂— or —(SiR⁰R⁰⁰—O)_(p1)—, in which p1 is an integer from1 to 12, q1 is an integer from 1 to 3, and R⁰ and R⁰⁰ have the meaningsindicated above.

Particularly preferred groups Sp and -Sp″—X″— are —(CH₂)_(p1)—,—(CH₂)_(p1)—O—, —(CH₂)_(p1)—O—CO—, —(CH₂)_(p1)—CO—O—,—(CH₂)_(p1)—O—OC—O—, in which p1 and q1 have the meanings indicatedabove.

Particularly preferred groups Sp″ are, in each case straight-chain,ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene,nonylene, decylene, undecylene, dodecylene, octadecylene,ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene,ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene,propenylene and butenylene.

In a preferred embodiment of the invention the compounds of formula Iand its subformulae contain a spacer group Sp that is substituted by oneor more polymerisable groups P, so that the group Sp-P corresponds toSp(P)_(s), with s being (branched polymerisable groups).

Preferred compounds of formula I according to this preferred embodimentare those wherein s is 2, i.e. compounds which contain a group Sp(P)₂.Very preferred compounds of formula I according to this preferredembodiment contain a group selected from the following formulae:—X-alkyl-CHPP  S1—X-alkyl-CH((CH₂)_(aa)P)((CH₂)_(bb)P)  S2—X—N((CH₂)_(aa)P)((CH₂)_(bb)P)  S3—X-alkyl-CHP—CH₂—CH₂P  S4—X-alkyl-C(CH₂P)(CH₂P)—C_(aa)H_(2aa+1)  S5—X-alkyl-CHP—CH₂P  S6—X-alkyl-CPP-C_(aa)H_(2aa+1)  S7—X-alkyl-CHPCHP-C_(aa)H_(2aa+1)  S8

-   in which P is as defined in formula I,-   alkyl denotes a single bond or straight-chain or branched alkylene    having 1 to 12 C atoms which is unsubstituted or mono- or    polysubstituted by F, Cl or CN and in which one or more non-adjacent    CH₂ groups may each, independently of one another, be replaced by    —C(R⁰)═C(R⁰)—, —C≡C—, —N(R⁰)—, —O—, —S—, —CO—, —CO—O—, —O—CO—,    —O—CO—O— in such a way that O and/or S atoms are not linked directly    to one another, where R⁰ has the meaning indicated above,-   aa and bb each, independently of one another, denote 0, 1, 2, 3, 4,    5 or 6,-   X has one of the meanings indicated for X″, and is preferably O, CO,    SO₂, O—CO—, CO—O or a single bond.

Preferred spacer groups Sp(P)₂ are selected from formulae S1, S2 and S3.

Very preferred spacer groups Sp(P)₂ are selected from the followingsubformulae:—CHPP  S1a—O—CHPP  S1b—CH₂—CHPP  S1c—OCH₂—CHPP  S1d—CH(CH₂—P)(CH₂—P)  S2a—OCH(CH₂—P)(CH₂—P)  S2b—CH₂—CH(CH₂—P)(CH₂—P)  S2c—OCH₂—CH(CH₂—P)(CH₂—P)  S2d—CO—NH((CH₂)₂P)((CH₂)₂P)  S3a

In the compounds of formula I and its subformulae as described above andbelow, P is preferably selected from the group consisting of vinyloxy,acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane andepoxide, most preferably from acrylate and methacrylate.

Further preferred are compounds of formula I and its subformulae asdescribed above and below, wherein all polymerisable groups P that arepresent in the compound have the same meaning, and very preferablydenote acrylate or methacrylate, most preferably methacrylate.

In the compounds of formula I and its subformulae as described above andbelow, R preferably denotes P-Sp-.

Further preferred are compounds of formula I and its subformulae asdescribed above and below, wherein Sp denotes a single bond or—(CH₂)_(p1)—, —O—(CH₂)_(p1)—, —O—CO—(CH₂)_(p1), or —CO—O—(CH₂)_(p1),wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is —O—(CH₂)_(p1)—,—O—CO—(CH₂)_(p1) or —CO—O—(CH₂)_(p1) the O-atom or CO-group,respectively, is linked to the benzene ring.

Further preferred are compounds of formula I and its subformulae asdescribed above and below, wherein at least one group Sp is a singlebond.

Further preferred are compounds of formula I and its subformulae asdescribed above and below, wherein at least one group Sp is differentfrom a single bond, and is preferably selected from —(CH₂)_(p1)—,—O—(CH₂)_(p1)—, —O—CO—(CH₂)_(p1), or —CO—O—(CH₂)_(p1), wherein p1 is 2,3, 4, 5 or 6, and, if Sp is —O(CH₂)_(p1)—, —O—CO—(CH₂)_(p1) or—CO—O—(CH₂)_(p1) the O-atom or CO-group, respectively, is linked to thebenzene ring.

Very preferred groups -A¹-(Z-A²)_(z)- in formula I are selected from thefollowing formulae

wherein at least one benzene ring is are substituted by at last onegroup L¹¹ and the benzene rings are optionally further substituted byone or more groups L or P-Sp-.

Preferred compounds of formula I are selected from the followingsubformulae

wherein P, Sp, R and L have the meanings given in formula I,r1, r3 are independently of each other 0, 1, 2 or 3,r2 is 0, 1, 2, 3 or 4,r4, r5, r6 are independently of each other 0, 1 or 2,wherein r1+r6≥1, r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1, and at least one groupL denotes —CH₂—O—CH₃, andwherein in formula I1 at least one of the groups Sp is a single bond.

Preferred are compounds of formula I1-I5 wherein one of the two groups Ris H and the other is P-Sp.

Further preferred are compounds of formula I1-I5 wherein both groups Rdenote H.

Further preferred are compounds of formula I1-I5 wherein both groups Rdenote P-Sp.

Very preferred are compounds of formula I1, I2 and I5.

Very preferred compounds of formula I and I1-I5 are selected from thefollowing subformulae:

wherein P, Sp, P(Sp)₂, L, r1-r6 have the meanings given in formula I andI1-I5, and at least one group L denotes —CH₂—O—CHs, and wherein informulae I1-1 to I1-4 at least one of the groups Sp is a single bond.

Very preferred compounds of formula I are selected from the followingsubformulae:

Wherein L^(a) is —CH₂—O—CHs, P, Sp and Sp(P)₂ have the meanings givenabove or below, with Sp preferably being different from a single bond,and L′ has one of the meanings given for L above or below that ispreferably different from L^(a).

Preferred compounds of formula I1 to I5, I1-1 to I5-5 and I1-1-1 toI5-5-7 are those wherein all groups Sp denote a single bond.

Further preferred compounds of formula I1 to I5, I1-1 to I5-5 and I1-1-1to I5-5-7 are those wherein at least one of the groups Sp is a singlebond and at least one of the groups Sp is different from a single bond.

Preferred compounds of formula I and II and their subformulae areselected from the following preferred embodiments, including anycombination thereof:

-   -   All groups P in the compound have the same meaning,    -   A¹-(Z-A²)_(z)- is selected from formulae A1, A2 and A5,    -   the compounds contain exactly two polymerizable groups        (represented by the groups P),    -   the compounds contain exactly three polymerizable groups        (represented by the groups P),    -   P is selected from the group consisting of acrylate,        methacrylate and oxetane, very preferably acrylate or        methacrylate,    -   P is methacrylate,    -   all groups Sp are a single bond,    -   at least one of the groups Sp is a single bond and at least one        of the groups Sp is different from a single bond,    -   Sp, when being different from a single bond, is —(CH₂)_(p2)—,        —(CH₂)_(p2)—O—, —(CH₂)_(p2)—CO—O—, —(CH₂)_(p2)—O—CO—, wherein p2        is 2, 3, 4, 5 or 6, and the O-atom or the CO-group,        respectively, is connected to the benzene ring,    -   Sp is a single bond or denotes —(CH₂)_(p2)—, —(CH₂)_(p2)—O—,        —(CH₂)_(p2)—CO—O—, —(CH₂)_(p2)—O—CO—, wherein p2 is 2, 3, 4, 5        or 6, and the O-atom or the CO-group, respectively, is connected        to the benzene ring,    -   Sp(P)₂ is selected from subformulae S11-S31,    -   R denotes P-Sp-,    -   R does not denote or contain a polymerizable group,    -   R does not denote or contain a polymerizable group and denotes        straight chain, branched or cyclic alkyl having 1 to 25 C atoms,        wherein one or more non-adjacent CH₂-groups are optionally        replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a        manner that O- and/or S-atoms are not directly connected with        each other, and wherein one or more H atoms are each optionally        replaced by F, Cl or L^(a),    -   L or L′, when being different from L¹¹, denote F, Cl or CN,    -   L′ is F,    -   r1, r2 and r3 denote 0 or 1,    -   r1, r2, r3, r4, r5 and r6 denote 0 or 1,    -   one of r1 and r6 is 0 and the other is 1,    -   r1 is 1, and r2 and r3 are 0,    -   r3 is 1 and r1 and r2 are 0,    -   one of r4 and r5 is 0 and the other is 1,    -   r1 and r4 are 0 and r3 is 1,    -   r1 and r3 are 0 and r4 is 1,    -   r3 and r4 are 0 and r1 is 1,

Preferred compounds of formula II are those selected from the abovepreferred subformulae I1 to I5, I1-1 to I5-5 and I1-1-1 to I5-5-7,wherein P is replaced by Pg as defined in formula II.

Suitable protected hydroxyl groups Pg for use in compounds of formula IIand its subformulae are known to the person skilled in the art.Preferred protecting groups for hydroxyl groups are alkyl, alkoxyalkyl,acyl, alkylsilyl, arylsilyl and arylmethyl groups, especially2-tetrahydropyranyl, methoxymethyl, methoxyethoxymethyl, acetyl,triisopropylsilyl, tert-butyldimethylsilyl or benzyl.

The term “masked hydroxyl group” is understood to mean any functionalgroup that can be chemically converted into a hydroxyl group. Suitablemasked hydroxyl groups Pg are known to the person skilled in the art.

The compounds of formula II are suitable as intermediates for thepreparation of compounds of the formula I and its subformulae.

The invention further relates to the use of the compounds of formula IIas intermediates for the preparation of compounds of the formula I andits subformulae.

The compounds and intermediates of the formulae I and II andsub-formulae thereof can be prepared analogously to processes known tothe person skilled in the art and described in standard works of organicchemistry, such as, for example, in Houben-Weyl, Methoden derorganischen Chemie [Methods of Organic Chemistry], Thieme-Verlag,Stuttgart.

For example, compounds of formula I can be synthesised by esterificationor etherification of the intermediates of formula II, wherein Pg denotesOH, using corresponding acids, acid derivatives, or halogenatedcompounds containing a polymerisable group P.

For example, acrylic or methacrylic esters can be prepared byesterification of the corresponding alcohols with acid derivatives like,for example, (meth)acryloyl chloride or (meth)acrylic anhydride in thepresence of a base like pyridine or triethyl amine, and4-(N,N-dimethylamino)pyridine (DMAP). Alternatively the esters can beprepared by esterification of the alcohols with (meth)acrylic acid inthe presence of a dehydrating reagent, for example according to Steglichwith dicyclohexylcarbodiimide (DCC),N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) orN-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride and DMAP.

Further suitable methods are shown in the examples.

For the production of PSA displays, the polymerisable compoundscontained in the LC medium are polymerised or crosslinked (if onecompound contains two or more polymerisable groups) by in-situpolymerisation in the LC medium between the substrates of the LCdisplay, optionally while a voltage is applied to the electrodes.

The structure of the PSA displays according to the invention correspondsto the usual geometry for PSA displays, as described in the prior artcited at the outset. Geometries without protrusions are preferred, inparticular those in which, in addition, the electrode on the colourfilter side is unstructured and only the electrode on the TFT side hasslots. Particularly suitable and preferred electrode structures forPS-VA displays are described, for example, in US 2006/0066793 A1.

A preferred PSA type LC display of the present invention comprises:

-   -   a first substrate including a pixel electrode defining pixel        areas, the pixel electrode being connected to a switching        element disposed in each pixel area and optionally including a        micro-slit pattern, and optionally a first alignment layer        disposed on the pixel electrode,    -   a second substrate including a common electrode layer, which may        be disposed on the entire portion of the second substrate facing        the first substrate, and optionally a second alignment layer,    -   an LC layer disposed between the first and second substrates and        including an LC medium comprising a polymerisable component A        and a liquid crystal component B as described above and below,        wherein the polymerisable component A may also be polymerised.

The first and/or second alignment layer controls the alignment directionof the LC molecules of the LC layer. For example, in PS-VA displays thealignment layer is selected such that it imparts to the LC moleculeshomeotropic (or vertical) alignment (i.e. perpendicular to the surface)or tilted alignment. Such an alignment layer may for example comprise apolyimide, which may also be rubbed, or may be prepared by aphotoalignment method.

The LC layer with the LC medium can be deposited between the substratesof the display by methods that are conventionally used by displaymanufacturers, for example the so-called one-drop-filling (ODF) method.The polymerisable component of the LC medium is then polymerised forexample by UV photopolymerisation. The polymerisation can be carried outin one step or in two or more steps.

The PSA display may comprise further elements, like a colour filter, ablack matrix, a passivation layer, optical retardation layers,transistor elements for addressing the individual pixels, etc., all ofwhich are well known to the person skilled in the art and can beemployed without inventive skill.

The electrode structure can be designed by the skilled person dependingon the individual display type. For example for PS-VA displays amulti-domain orientation of the LC molecules can be induced by providingelectrodes having slits and/or bumps or protrusions in order to createtwo, four or more different tilt alignment directions.

Upon polymerisation the polymerisable compounds form a crosslinkedpolymer, which causes a certain pretilt of the LC molecules in the LCmedium. Without wishing to be bound to a specific theory, it is believedthat at least a part of the crosslinked polymer, which is formed by thepolymerisable compounds, will phase-separate or precipitate from the LCmedium and form a polymer layer on the substrates or electrodes, or thealignment layer provided thereon. Microscopic measurement data (like SEMand AFM) have confirmed that at least a part of the formed polymeraccumulates at the LC/substrate interface.

The polymerisation can be carried out in one step. It is also possiblefirstly to carry out the polymerisation, optionally while applying avoltage, in a first step in order to produce a pretilt angle, andsubsequently, in a second polymerisation step without an appliedvoltage, to polymerise or crosslink the compounds which have not reactedin the first step (“end curing”).

Suitable and preferred polymerisation methods are, for example, thermalor photopolymerisation, preferably photopolymerisation, in particular UVinduced photopolymerisation, which can be achieved by exposure of thepolymerisable compounds to UV radiation.

Optionally one or more polymerisation initiators are added to the LCmedium. Suitable conditions for the polymerisation and suitable typesand amounts of initiators are known to the person skilled in the art andare described in the literature. Suitable for free-radicalpolymerisation are, for example, the commercially availablephotoinitiators Irgacure651®, Irgacure184®, Irgacure907®, Irgacure369®or Darocure1173® (Ciba AG). If a polymerisation initiator is employed,its proportion is preferably 0.001 to 5% by weight, particularlypreferably 0.001 to 1% by weight.

The polymerisable compounds according to the invention are also suitablefor polymerisation without an initiator, which is accompanied byconsiderable advantages, such, for example, lower material costs and inparticular less contamination of the LC medium by possible residualamounts of the initiator or degradation products thereof. Thepolymerisation can thus also be carried out without the addition of aninitiator. In a preferred embodiment, the LC medium thus does notcontain a polymerisation initiator.

The the LC medium may also comprise one or more stabilisers in order toprevent undesired spontaneous polymerisation of the RMs, for exampleduring storage or transport. Suitable types and amounts of stabilisersare known to the person skilled in the art and are described in theliterature. Particularly suitable are, for example, the commerciallyavailable stabilisers from the Irganox® series (Ciba AG), such as, forexample, Irganox® 1076. If stabilisers are employed, their proportion,based on the total amount of RMs or the polymerisable component(component A), is preferably 10-500,000 ppm, particularly preferably50-50,000 ppm.

The polymerisable compounds of formula I do in particular show good UVabsorption in, and are therefore especially suitable for, a process ofpreparing a PSA display including one or more of the following features:

-   -   the polymerisable medium is exposed to UV light in the display        in a 2-step process, including a first UV exposure step (“UV-1        step”) to generate the tilt angle, and a second UV exposure step        (“UV-2 step”) to finish polymerization,    -   the polymerisable medium is exposed to UV light in the display        generated by an energy-saving UV lamp (also known as “green UV        lamps”). These lamps are characterized by a relative low        intensity ( 1/100- 1/10 of a conventional UV1 lamp) in their        absorption spectra from 300-380 nm, and are preferably used in        the UV2 step, but are optionally also used in the UV1 step when        avoiding high intensity is necessary for the process.    -   the polymerisable medium is exposed to UV light in the display        generated by a UV lamp with a radiation spectrum that is shifted        to longer wavelengths, preferably 340 nm or more, to avoid short        UV light exposure in the PS-VA process.

Both using lower intensity and a UV shift to longer wavelengths protectthe organic layer against damage that may be caused by the UV light.

A preferred embodiment of the present invention relates to a process forpreparing a PSA display as described above and below, comprising one ormore of the following features:

-   -   the polymerisable LC medium is exposed to UV light in a 2-step        process, including a first UV exposure step (“UV-1 step”) to        generate the tilt angle, and a second UV exposure step (“UV-2        step”) to finish polymerization,    -   the polymerisable LC medium is exposed to UV light generated by        a UV lamp having an intensity of from 0.5 mW/cm² to 10 mW/cm² in        the wavelength range from 300-380 nm, preferably used in the UV2        step, and optionally also in the UV1 step,    -   the polymerisable LC medium is exposed to UV light having a        wavelength of 340 nm or more, and preferably 400 nm or less.

This preferred process can be carried out for example by using thedesired UV lamps or by using a band pass filter and/or a cut-off filter,which are substantially transmissive for UV light with the respectivedesired wavelength(s) and are substantially blocking light with therespective undesired wavelengths. For example, when irradiation with UVlight of wavelengths λ of 300-400 nm is desired, UV exposure can becarried out using a wide band pass filter being substantiallytransmissive for wavelengths 300 nm<λ<400 nm. When irradiation with UVlight of wavelength λ of more than 340 nm is desired, UV exposure can becarried out using a cut-off filter being substantially transmissive forwavelengths λ>340 nm.

“Substantially transmissive” means that the filter transmits asubstantial part, preferably at least 50% of the intensity, of incidentlight of the desired wavelength(s). “Substantially blocking” means thatthe filter does not transmit a substantial part, preferably at least 50%of the intensity, of incident light of the undesired wavelengths.“Desired (undesired) wavelength” e.g. in case of a band pass filtermeans the wavelengths inside (outside) the given range of λ, and in caseof a cut-off filter means the wavelengths above (below) the given valueof λ.

This preferred process enables the manufacture of displays by usinglonger UV wavelengths, thereby reducing or even avoiding the hazardousand damaging effects of short UV light components.

UV radiation energy is in general from 6 to 100 J, depending on theproduction process conditions.

Preferably the LC medium according to the present invention doesessentially consist of a polymerisable component A), or one or morepolymerisable compounds of formula I, and an LC component B), or LC hostmixture, as described above and below. However, the LC medium mayadditionally comprise one or more further components or additives,preferably selected from the list including but not limited toco-monomers, chiral dopants, polymerisation initiators, inhibitors,stabilizers, surfactants, wetting agents, lubricating agents, dispersingagents, hydrophobing agents, adhesive agents, flow improvers, defoamingagents, deaerators, diluents, reactive diluents, auxiliaries,colourants, dyes, pigments and nanoparticles.

Particular preference is given to LC media comprising one, two or threepolymerisable compounds of formula I.

Preference is furthermore given to LC media in which the polymerisablecomponent A) comprises exclusively polymerisable compounds of formula I.

Preference is furthermore given to LC media in which theliquid-crystalline component B) or the LC host mixture has a nematic LCphase, and preferably has no chiral liquid crystal phase.

The LC component B), or LC host mixture, is preferably a nematic LCmixture.

Preference is furthermore given to achiral compounds of formula I, andto LC media in which the compounds of component A and/or B are selectedexclusively from the group consisting of achiral compounds.

Preferably the proportion of the polymerisable component A) in the LCmedium is from >0 to <5%, very preferably from >0 to <1%, mostpreferably from 0.01 to 0.5%.

Preferably the proportion of compounds of formula I in the LC medium isfrom >0 to <5%, very preferably from >0 to <1%, most preferably from0.01 to 0.5%.

Preferably the proportion of the LC component B) in the LC medium isfrom 95 to <100%, very preferably from 99 to <100%.

In a preferred embodiment the polymerisable compounds of thepolymerisable component B) are exclusively selected from formula I.

In another preferred embodiment the polymerisable component B)comprises, in addition to the compounds of formula I, one or morefurther polymerisable compounds (“co-monomers”), preferably selectedfrom RMs.

Suitable and preferred mesogenic comonomers are selected from thefollowing formulae:

in which the individual radicals have the following meanings:

-   P¹, P² and P³ each, independently of one another, denote an acrylate    or methacrylate group,-   Sp¹, Sp² and Sp³ each, independently of one another, denote a single    bond or a spacer group having one of the meanings indicated above    and below for Sp, and particularly preferably denote —(CH₂)_(p1)—,    —(CH₂)_(p1)—O—, —(CH₂)_(p1)—CO—O—, —(CH₂)_(p1)—O—CO— or    —(CH₂)_(p1)—O—CO—O—, in which p1 is an integer from 1 to 12, where,    in addition, one or more of the radicals P¹-Sp¹-, P¹-Sp²- and    P³-Sp³- may denote R^(aa), with the proviso that at least one of the    radicals P¹-Sp¹-, P²-Sp² and P³-Sp³- present is different from    R^(aa),-   R^(aa) denotes H, F, Cl, CN or straight-chain or branched alkyl    having 1 to 25 C atoms, in which, in addition, one or more    non-adjacent CH₂ groups may each be replaced, independently of one    another, by C(R⁰)═C(R⁰⁰)—, —C≡C—, —N(R⁰)—, —O—, —S—, —CO—, —CO—O—,    —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked    directly to one another, and in which, in addition, one or more H    atoms may be replaced by F, Cl, CN or P¹-Sp¹-, particularly    preferably straight-chain or branched, optionally mono- or    polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl,    alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12    C atoms (where the alkenyl and alkynyl radicals have at least two C    atoms and the branched radicals have at least three C atoms),-   R⁰, R⁰⁰ each, independently of one another and identically or    differently on each occurrence, denote H or alkyl having 1 to 12 C    atoms,-   R^(y) and R^(z) each, independently of one another, denote H, F, CH₃    or CF₃,-   X¹, X² and X³ each, independently of one another, denote —CO—O—,    —O—CO— or a single bond,-   Z¹ denotes —O—, —CO—, —C(R^(y)R^(z))— or —CF₂CF₂—,-   Z² and Z³ each, independently of one another, denote —CO—O—, —O—CO—,    —CH₂O—, —OCH₂—, —CF₂O—, —OCF₂— or —(CH₂)_(n)−, where n is 2, 3 or 4,-   L on each occurrence, identically or differently, denotes F, Cl, CN    or straight-chain or branched, optionally mono- or polyfluorinated    alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl,    alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms,    preferably F,-   L′ and L″ each, independently of one another, denote H, F or Cl,-   r denotes 0, 1, 2, 3 or 4,-   s denotes 0, 1, 2 or 3,-   t denotes 0, 1 or 2,-   x denotes 0 or 1.

Especially preferred are compounds of formulae M2, M13, M17, M22, M23,M24 and M30.

Further preferred are trireactive compounds M15 to M30, in particularM17, M18, M19, M22, M23, M24, M25, M26, M30 and M31.

In the compounds of formulae M1 to M31 the group

is preferably

wherein L on each occurrence, identically or differently, has one of themeanings given above or below, and is preferably F, Cl, CN, NO₂, CH₃,C₂H₅, C(CH₃)₃, CH(CH₃)₂, CH₂CH(CH₃)C₂H₅, OCH₃, OC₂H₅, COCH₃, COC₂H₅,COOCH₃, COOC₂H₅, CF₃, OCF₃, OCHF₂, OC₂F₅ or P-Sp-, very preferably F,Cl, CN, CH₃, C₂H₅, OCH₃, COCH₃, OCF₃ or P-Sp-, more preferably F, Cl,CH₃, OCH₃, COCH₃ oder OCF₃, especially F or CH₃.

Besides the polymerisable compounds described above, the LC media foruse in the LC displays according to the invention comprise an LC mixture(“host mixture”) comprising one or more, preferably two or more LCcompounds which are selected from low-molecular-weight compounds thatare unpolymerisable. These LC compounds are selected such that theystable and/or unreactive to a polymerisation reaction under theconditions applied to the polymerisation of the polymerisable compounds.

In principle, any LC mixture which is suitable for use in conventionaldisplays is suitable as host mixture. Suitable LC mixtures are known tothe person skilled in the art and are described in the literature, forexample mixtures in VA displays in EP 1 378 557 A1 and mixtures for OCBdisplays in EP 1 306 418 A1 and DE 102 24 046 A1.

The polymerisable compounds of formula I are especially suitable for usein an LC host mixture that comprises one or more mesogenic or LCcompounds comprising an alkenyl group (hereinafter also referred to as“alkenyl compounds”), wherein said alkenyl group is stable to apolymerisation reaction under the conditions used for polymerisation ofthe compounds of formula I and of the other polymerisable compoundscontained in the LC medium. Compared to RMs known from prior art thecompounds of formula I do in such an LC host mixture exhibit improvedproperties, like solubility, reactivity or capability of generating atilt angle.

Thus, in addition to the polymerisable compounds of formula I, the LCmedium according to the present invention comprises one or moremesogenic or liquid crystalline compounds comprising an alkenyl group,(“alkenyl compound”), where this alkenyl group is preferably stable to apolymerisation reaction under the conditions used for the polymerisationof the polymerisable compounds of formula I or of the otherpolymerisable compounds contained in the LC medium.

The alkenyl groups in the alkenyl compounds are preferably selected fromstraight-chain, branched or cyclic alkenyl, in particular having 2 to 25C atoms, particularly preferably having 2 to 12 C atoms, in which, inaddition, one or more non-adjacent CH₂ groups may be replaced by —O—,—S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atomsare not linked directly to one another, and in which, in addition, oneor more H atoms may be replaced by F and/or C₁.

Preferred alkenyl groups are straight-chain alkenyl having 2 to 7 Catoms and cyclohexenyl, in particular ethenyl, propenyl, butenyl,pentenyl, hexenyl, heptenyl, 1,4-cyclohexen-1-yl and1,4-cyclohexen-3-yl.

The concentration of compounds containing an alkenyl group in the LChost mixture (i.e. without any polymerisable compounds) is preferablyfrom 5% to 100%, very preferably from 20% to 60%.

Especially preferred are LC mixtures containing 1 to 5, preferably 1, 2or 3 compounds having an alkenyl group.

The mesogenic and LC compounds containing an alkenyl group arepreferably selected from formulae AN and AY as defined below.

Besides the polymerisable component A) as described above, the LC mediaaccording to the present invention comprise an LC component B), or LChost mixture, comprising one or more, preferably two or more LCcompounds which are selected from low-molecular-weight compounds thatare unpolymerisable. These LC compounds are selected such that theystable and/or unreactive to a polymerisation reaction under theconditions applied to the polymerisation of the polymerisable compounds.

In a first preferred embodiment the LC medium contains an LC componentB), or LC host mixture, based on compounds with negative dielectricanisotropy. Such LC media are especially suitable for use in PS-VA andPS-UB-FFS displays. Particularly preferred embodiments of such an LCmedium are those of sections a)-z3) below:

-   a) LC medium wherein the component B) or LC host mixture comprises    one or more compounds selected from formulae CY and PY:

-   -   wherein    -   a denotes 1 or 2,    -   b denotes 0 or 1,

denotes

-   -   R¹ and R² each, independently of one another, denote alkyl        having 1 to 12 C atoms, where, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —OCO— or —COO— in such a way that O atoms are not linked        directly to one another, preferably alkyl or alkoxy having 1 to        6 C atoms,    -   Z^(x) and Z^(y) each, independently of one another, denote        —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—,        —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,        preferably a single bond,    -   L¹⁻⁴ each, independently of one another, denote F, Cl, OCF₃,        CF₃, CH₃, CH₂F, CHF₂.

Preferably, both L¹ and L² denote F or one of L¹ and L² denotes F andthe other denotes Cl, or both L³ and L⁴ denote F or one of L³ and L⁴denotes F and the other denotes Cl.

The compounds of the formula CY are preferably selected from the groupconsisting of the following sub-formulae:

in which a denotes 1 or 2, alkyl and alkyl* each, independently of oneanother, denote a straight-chain alkyl radical having 1-6 C atoms, andalkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and(O) denotes an oxygen atom or a single bond. Alkenyl preferably denotesCH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

The compounds of the formula PY are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms, and (O) denotes anoxygen atom or a single bond. Alkenyl preferably denotes CH₂═CH—,CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

-   b) LC medium wherein the component B) or LC host mixture comprises    one or more mesogenic or LC compounds comprising an alkenyl group    (hereinafter also referred to as “alkenyl compounds”), wherein said    alkenyl group is stable to a polymerisation reaction under the    conditions used for polymerisation of the polymerisable compounds    contained in the LC medium.

Preferably the component B) or LC host mixture comprises one or morealkenyl compounds selected from formulae AN and AY

in which the individual radicals, on each occurrence identically ordifferently, and each, independently of one another, have the followingmeaning:

-   R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the    rings X, Y and Z denotes cyclohexenyl, also one of the meanings of    R^(A2),-   R^(A2) alkyl having 1 to 12 C atoms, in which, in addition, one or    two non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,    —OCO— or —COO— in such a way that O atoms are not linked directly to    one another,-   Z^(x) —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—,    —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O—, or a single bond, preferably    a single bond,-   L^(1,2) H, F, Cl, OCF₃, CF₃, CH₃, CH₂F or CHF₂H, preferably H, F or    Cl,-   x 1 or 2,-   z 0 or 1.

Preferred compounds of formula AN and AY are those wherein R^(A2) isselected from ethenyl, propenyl, butenyl, pentenyl, hexenyl andheptenyl.

In a preferred embodiment the component B) or LC host mixture comprisesone or more compounds of formula AN selected from the followingsub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Preferably the the component B) or LC host mixture comprises one or morecompounds selected from formulae AN1, AN2, AN3 and AN6, very preferablyone or more compounds of formula AN1.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds of formula AN selected from thefollowing sub-formulae:

in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, andR^(b1) denotes H, CH₃ or C₂H₅.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds selected from the following subformulae:

Most preferred are compounds of formula AN1a2 and AN1a5.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds of formula AY selected from thefollowing sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, “(O)” denotes an O-atomor a single bond, and alkenyl and alkenyl* each, independently of oneanother, denote a straight-chain alkenyl radical having 2-7 C atoms.Alkenyl and alkenyl* preferably denote CH₂═CH—, CH₂═CHCH₂CH₂—,CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₂—CH═CH—(CH₂)₂.

In another preferred embodiment the component B) or LC host mixturecomprises one or more compounds of formula AY selected from thefollowing sub-formulae:

in which m and n each, independently of one another, denote 1, 2, 3, 4,5 or 6, and alkenyl denotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

Preferably the proportion of compounds of formula AN and AY in the LCmedium is from 2 to 70% by weight, very preferably from 5 to 60% byweight, most preferably from 10 to 50% by weight.

Preferably the LC medium or LC host mixture contains 1 to 5, preferably1, 2 or 3 compounds selected from formulae AN and AY.

In another preferred embodiment of the present invention the LC mediumcomprises one or more compounds of formula AY14, very preferably ofAY14a. The proportion of compounds of formula AY14 or AY14a in the LCmedium is preferably 3 to 20% by weight.

The addition of alkenyl compounds of formula AN and/or AY enables areduction of the viscosity and response time of the LC medium.

-   c) LC medium wherein the component B) or LC host mixture comprises    one or more compounds of the following formula:

in which the individual radicals have the following meanings:

denotes

denotes

-   R³ and R⁴ each, independently of one another, denote alkyl having 1    to 12 C atoms, in which, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in    such a way that O atoms are not linked directly to one another,-   Z^(y) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,    —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,    preferably a single bond.

The compounds of the formula ZK are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Especially preferred are compounds of formula ZK1.

Particularly preferred compounds of formula ZK are selected from thefollowing sub-formulae:

wherein the propyl, butyl and pentyl groups are straight-chain groups.

Most preferred are compounds of formula ZK1a.

-   d) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of the following    formula:

in which the individual radicals on each occurrence, identically ordifferently, have the following meanings:

-   R⁵ and R⁶ each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,

denotes

denotes

and

-   e denotes 1 or 2.

The compounds of the formula DK are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

-   e) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of the following    formula:

in which the individual radicals have the following meanings:

denotes

with at least one ring F being different from cyclohexylene,

-   f denotes 1 or 2,-   R¹ and R² each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,-   Z^(x) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,    —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,    preferably a single bond,-   L¹ and L² each, independently of one another, denote F, Cl, OCF₃,    CF₃, CH₃, CH₂F, CHF₂.

Preferably, both radicals L¹ and L² denote F or one of the radicals L¹and L² denotes F and the other denotes Cl.

The compounds of the formula LY are preferably selected from the groupconsisting of the following sub-formulae:

in which R¹ has the meaning indicated above, alkyl denotes astraight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygenatom or a single bond, and v denotes an integer from 1 to 6. R¹preferably denotes straight-chain alkyl having 1 to 6 C atoms orstraight-chain alkenyl having 2 to 6 C atoms, in particular CH₃, C₂H₅,n-C₃H₇, n-C₄H₉, n-C₅H₁₁, CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

-   f) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which alkyl denotes C₁₋₆-alkyl, L^(x) denotes H or F, and X denotesF, Cl, OCF₃, OCHF₂ or OCH═CF₂. Particular preference is given tocompounds of the formula G1 in which X denotes F.

-   g) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which R⁵ has one of the meanings indicated above for R¹, alkyldenotes C₁₋₆-alkyl, d denotes 0 or 1, and z and m each, independently ofone another, denote an integer from 1 to 6. R⁵ in these compounds isparticularly preferably C₁₋₆-alkyl or -alkoxy or C₂₋₆-alkenyl, d ispreferably 1. The LC medium according to the invention preferablycomprises one or more compounds of the above-mentioned formulae inamounts of 5% by weight.

-   h) LC medium wherein component B) or the LC host mixture    additionally comprises one or more biphenyl compounds selected from    the group consisting of the following formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

The proportion of the biphenyls of the formulae B1 to B3 in the LC hostmixture is preferably at least 3% by weight, in particular 5% by weight.

The compounds of the formula B2 are particularly preferred.

The compounds of the formulae B1 to B3 are preferably selected from thegroup consisting of the following sub-formulae:

in which alkyl* denotes an alkyl radical having 1-6 C atoms. The mediumaccording to the invention particularly preferably comprises one or morecompounds of the formulae B1a and/or B2c.

-   i) LC medium wherein component B) or the LC host mixture    additionally comprises one or more terphenyl compounds of the    following formula:

in which R⁵ and R⁶ each, independently of one another, have one of themeanings indicated above, and

each, independently of one another, denote

in which L⁵ denotes F or Cl, preferably F, and L⁶ denotes F, Cl, OCF₃,CF₃, CH₃, CH₂F or CHF₂, preferably F.

The compounds of the formula T are preferably selected from the groupconsisting of the following sub-formulae:

in which R denotes a straight-chain alkyl or alkoxy radical having 1-7 Catoms, R* denotes a straight-chain alkenyl radical having 2-7 C atoms,(O) denotes an oxygen atom or a single bond, and m denotes an integerfrom 1 to 6. R* preferably denotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

R preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl,methoxy, ethoxy, propoxy, butoxy or pentoxy.

The LC host mixture according to the invention preferably comprises theterphenyls of the formula T and the preferred sub-formulae thereof in anamount of 0.5-30% by weight, in particular 1-20% by weight.

Particular preference is given to compounds of the formulae T1, T2, T3and T21. In these compounds, R preferably denotes alkyl, furthermorealkoxy, each having 1-5 C atoms.

The terphenyls are preferably employed in LC media according to theinvention if the Δn value of the mixture is to be 0.1. Preferred LCmedia comprise 2-20% by weight of one or more terphenyl compounds of theformula T, preferably selected from the group of compounds T1 to T22.

-   k) LC medium wherein component B) or the LC host mixture    additionally comprises one or more quaterphenyl compounds selected    from the group consisting of the following formulae:

wherein

-   R^(Q) is alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C    atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which    are optionally fluorinated,-   X^(Q) is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   L^(Q1) to L^(Q6) independently of each other are H or F, with at    least one of L^(Q1) to L^(Q6) being F.

Preferred compounds of formula Q are those wherein R^(Q) denotesstraight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl,n-propyl or n-butyl.

Preferred compounds of formula Q are those wherein L^(Q3) and L^(Q4) areF. Further preferred compounds of formula Q are those wherein L^(Q3),L^(Q4) and one or two of L^(Q1) and L^(Q2) are F.

Preferred compounds of formula Q are those wherein X^(Q) denotes F orOCF₃, very preferably F.

The compounds of formula Q are preferably selected from the followingsubformulae

wherein R^(Q) has one of the meanings of formula Q or one of itspreferred meanings given above and below, and is preferably ethyl,n-propyl or n-butyl.

Especially preferred are compounds of formula Q1, in particular thosewherein R^(Q) is n-propyl.

Preferably the proportion of compounds of formula Q in the LC hostmixture is from >0 to ≤5% by weight, very preferably from 0.1 to 2% byweight, most preferably from 0.2 to 1.5% by weight.

Preferably the LC host mixture contains 1 to 5, preferably 1 or 2compounds of formula Q.

The addition of quaterphenyl compounds of formula Q to the LC hostmixture enables to reduce ODF mura, whilst maintaining high UVabsorption, enabling quick and complete polymerisation, enabling strongand quick tilt angle generation, and increasing the UV stability of theLC medium.

Besides, the addition of compounds of formula Q, which have positivedielectric anisotropy, to the LC medium with negative dielectricanisotropy allows a better control of the values of the dielectricconstants ε_(∥) and ε_(⊥), and in particular enables to achieve a highvalue of the dielectric constant ε_(∥) while keeping the dielectricanisotropy Δε constant, thereby reducing the kick-back voltage andreducing image sticking.

-   l) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of formula C:

wherein

-   R^(C) denotes alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C    atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which    are optionally fluorinated,-   X^(C) denotes F, Cl, halogenated alkyl or alkoxy having 1 to 6 C    atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   L^(C1), L^(C2) independently of each other denote H or F, with at    least one of L^(C1) and L^(C2) being F.

Preferred compounds of formula C are those wherein R^(C) denotesstraight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl,n-propyl or n-butyl.

Preferred compounds of formula C are those wherein L^(C1) and L^(C2) areF.

Preferred compounds of formula C are those wherein X^(C) denotes F orOCF₃, very preferably F.

Preferred compounds of formula C are selected from the following formula

wherein R^(C) has one of the meanings of formula C or one of itspreferred meanings given above and below, and is preferably ethyl,n-propyl or n-butyl, very preferably n-propyl.

Preferably the proportion of compounds of formula C in the LC hostmixture is from >0 to ≤10% by weight, very preferably from 0.1 to 8% byweight, most preferably from 0.2 to 5% by weight.

Preferably the LC host mixture contains 1 to 5, preferably 1, 2 or 3compounds of formula C.

The addition of compounds of formula C, which have positive dielectricanisotropy, to the LC medium with negative dielectric anisotropy allowsa better control of the values of the dielectric constants ε_(∥) andε_(⊥), and in particular enables to achieve a high value of thedielectric constant ε_(∥) while keeping the dielectric anisotropy Δεconstant, thereby reducing the kick-back voltage and reducing imagesticking. Besides, the addition of compounds of formula C enables toreduce the viscosity and the response time of the LC medium.

-   m) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which R¹ and R² have the meanings indicated above and preferablyeach, independently of one another, denote straight-chain alkyl having 1to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

Preferred media comprise one or more compounds selected from theformulae O1, O3 and O4.

-   n) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds of the following    formula:

in which

denotes

R⁹ denotes H, CH₃, C₂H₅ or n-C₃H₇, (F) denotes an optional fluorinesubstituent, and q denotes 1, 2 or 3, and R⁷ has one of the meaningsindicated for R¹, preferably in amounts of >3% by weight, in particular≥5% by weight and very particularly preferably 5-30% by weight.

Particularly preferred compounds of the formula FI are selected from thegroup consisting of the following sub-formulae:

in which R⁷ preferably denotes straight-chain alkyl, and R⁹ denotes CH₃,C₂H₅ or n-C₃H₇. Particular preference is given to the compounds of theformulae FI1, FI2 and FI3.

-   o) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds selected from the group    consisting of the following formulae:

in which R⁹ has the meaning indicated for R¹, and alkyl denotes astraight-chain alkyl radical having 1-6 C atoms.

-   p) LC medium wherein component B) or the LC host mixture    additionally comprises one or more compounds which contain a    tetrahydronaphthyl or naphthyl unit, such as, for example, the    compounds selected from the group consisting of the following    formulae:

-   in which-   R¹⁰ and R¹¹ each, independently of one another, denote alkyl having    1 to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,-   and R¹⁰ and R¹¹ preferably denote straight-chain alkyl or alkoxy    having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C    atoms, and-   Z¹ and Z² each, independently of one another, denote —C₂H₄—,    —CH═CH—, —(CH₂)₄—, —(CH₂)₃O—, —O(CH₂)₃—, —CH═CH—CH₂CH₂—,    —CH₂CH₂CH═CH—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—,    —CF═CH—, —CH═CF—, —CH₂— or a single bond.-   q) LC medium wherein component B) or the LC host mixture    additionally comprises one or more difluorodibenzochromans and/or    chromans of the following formulae:

in which

-   R¹¹ and R¹² each, independently of one another, have one of the    meanings indicated above for R¹¹,-   ring M is trans-1,4-cyclohexylene or 1,4-phenylene,-   Z^(m) —C₂H₄—, —CH₂O—, —OCH₂—, —CO—O— or —O—CO—,-   c is 0, 1 or 2,-   preferably in amounts of 3 to 20% by weight, in particular in    amounts of 3 to 15% by weight.

Particularly preferred compounds of the formulae BC, CR and RC areselected from the group consisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygenatom or a single bond, c is 1 or 2, and alkenyl and alkenyl* each,independently of one another, denote a straight-chain alkenyl radicalhaving 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH₂═CH—,CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very particular preference is given to LC host mixtures comprising one,two or three compounds of the formula BC-2.

-   r) LC medium wherein component B) or the LC host mixture    additionally comprises one or more fluorinated phenanthrenes and/or    dibenzofurans of the following formulae:

in which R¹¹ and R¹² each, independently of one another, have one of themeanings indicated above for R¹¹, b denotes 0 or 1, L denotes F, and rdenotes 1, 2 or 3.

Particularly preferred compounds of the formulae PH and BF are selectedfrom the group consisting of the following sub-formulae:

in which R and R′ each, independently of one another, denote astraight-chain alkyl or alkoxy radical having 1-7 C atoms.

-   s) LC medium wherein component B) or the LC host mixture    additionally comprises one or more monocyclic compounds of the    following formula

wherein

-   R¹ and R² each, independently of one another, denote alkyl having 1    to 12 C atoms, where, in addition, one or two non-adjacent CH₂    groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such    a way that O atoms are not linked directly to one another,    preferably alkyl or alkoxy having 1 to 6 C atoms,-   L¹ and L² each, independently of one another, denote F, Cl, OCF₃,    CF₃, CH₃, CH₂F, CHF₂.

Preferably, both L¹ and L² denote F or one of L¹ and L² denotes F andthe other denotes Cl,

The compounds of the formula Y are preferably selected from the groupconsisting of the following sub-formulae:

in which, Alkyl and Alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes astraight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl*each, independently of one another, denote a straight-chain alkenylradical having 2-6 C atoms, and O denotes an oxygen atom or a singlebond. Alkenyl and Alkenyl* preferably denote CH₂═CH—, CH₂═CHCH₂CH₂—,CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

Particularly preferred compounds of the formula Y are selected from thegroup consisting of the following sub-formulae:

wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5C atoms.

-   t) LC medium which, apart from the polymerisable compounds as    described above and below, does not contain a compound which    contains a terminal vinyloxy group (—O—CH═CH₂).-   u) LC medium wherein component B) or the LC host mixture comprises 1    to 8, preferably 1 to 5, compounds of the formulae CY1, CY2, PY1    and/or PY2. The proportion of these compounds in the LC host mixture    as a whole is preferably 5 to 60%, particularly preferably 10 to    35%. The content of these individual compounds is preferably in each    case 2 to 20%.-   v) LC medium wherein component B) or the LC host mixture comprises 1    to 8, preferably 1 to 5, compounds of the formulae CY9, CY10, PY9    and/or PY10. The proportion of these compounds in the LC host    mixture as a whole is preferably 5 to 60%, particularly preferably    10 to 35%. The content of these individual compounds is preferably    in each case 2 to 20%.-   w) LC medium wherein component B) or the LC host mixture comprises 1    to 10, preferably 1 to 8, compounds of the formula ZK, in particular    compounds of the formulae ZK1, ZK2 and/or ZK6. The proportion of    these compounds in the LC host mixture as a whole is preferably 3 to    25%, particularly preferably 5 to 45%. The content of these    individual compounds is preferably in each case 2 to 20%.-   x) LC medium in which the proportion of compounds of the formulae    CY, PY and ZK in the LC host mixture as a whole is greater than 70%,    preferably greater than 80%.-   y) LC medium in which the LC host mixture contains one or more    compounds containing an alkenyl group, preferably selected from    formulae AN and AY, very preferably selected from formulae AN1, AN3,    AN6 and AY14, most preferably from formulae AN1a, AN3a, AN6a and    AY14. The concentration of these compounds in the LC host mixture is    preferably from 2 to 70%, very preferably from 3 to 55%.-   z) LC medium wherein component B) or the LC host mixture contains    one or more, preferably 1 to 5, compounds selected of formula    PY1-PY8, very preferably of formula PY2. The proportion of these    compounds in the LC host mixture as a whole is preferably 1 to 30%,    particularly preferably 2 to 20%. The content of these individual    compounds is preferably in each case 1 to 20%.-   z1) LC medium wherein component B) or the LC host mixture contains    one or more, preferably 1, 2 or 3, compounds selected from formulae    T1, T2 and T5, very preferably from formula T2. The content of these    compounds in the LC host mixture as a whole is preferably 1 to 20%.-   z2) LC medium in which the LC host mixture contains one or more    compounds selected from formulae CY and PY, one or more compounds    selected from formulae AN and AY, and one or more compounds selected    from formulae T and Q.-   z3) LC medium in which the LC host mixture contains one or more,    preferably 1, 2 or 3, compounds of formula BF1, and one or more,    preferably 1, 2 or 3, compounds selected from formulae AY14, AY15    and AY16, very preferably of formula AY14. The proportion of the    compounds of formula AY14-AY16 in the LC host mixture is preferably    from 2 to 35%, very preferably from 3 to 30%. The proportion of the    compounds of formula BF1 in the LC host mixture is preferably from    0.5 to 20%, very preferably from 1 to 15%. Further preferably the LC    host mixture according to this preferred embodiment contains one or    more, preferably 1, 2 or 3 compounds of formula T, preferably    selected from formula T1, T2 and T5, very preferably from formula T2    or T5. The proportion of the compounds of formula T in the LC host    mixture medium is preferably from 0.5 to 15%, very preferably from 1    to 10%.

In a second preferred embodiment the LC medium contains an LC hostmixture based on compounds with positive dielectric anisotropy. Such LCmedia are especially suitable for use in PS-OCB-, PS-TN-, PS-Posi-VA-,PS-IPS- or PS-FFS-displays.

in which the individual radicals have, independently of each other andon each occurrence identically or differently, the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

-   R²¹, R³¹ each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   X⁰ F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   Z³¹ —CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O— or    a single bond, preferably —CH₂CH₂—, —COO—, trans-CH═CH— or a single    bond, particularly preferably —COO—, trans-CH═CH— or a single bond,-   L²¹, L²², L³¹, L³² each, independently of one another, H or F,-   g 0, 1, 2 or 3.

In the compounds of formula A and B, X⁰ is preferably F, Cl, CF₃, CHF₂,OCF₃, OCHF₂, OCFHCF₃, OCFHCHF₂, OCFHCHF₂, OCF₂CH₃, OCF₂CHF₂, OCF₂CHF₂,OCF₂CF₂CHF₂, OCF₂CF₂CHF₂, OCFHCF₂CF₃, OCFHCF₂CHF₂, OCF₂CF₂CF₃,OCF₂CF₂CClF₂, OCClFCF₂CF₃ or CH═CF₂, very preferably F or OCF₃, mostpreferably F.

In the compounds of formula A and B, R²¹ and R³¹ are preferably selectedfrom straight-chain alkyl or alkoxy with 1, 2, 3, 4, 5 or 6 C atoms, andstraight-chain alkenyl with 2, 3, 4, 5, 6 or 7 C atoms.

In the compounds of formula A and B, g is preferably 1 or 2.

In the compounds of formula B, Z³¹ is preferably COO, trans-CH═CH or asingle bond, very preferably COO or a single bond.

Preferably component B) of the LC medium comprises one or more compoundsof formula A selected from the group consisting of the followingformulae:

in which A²¹, R²¹, X⁰, L²¹ and L²² have the meanings given in formula A,L²³ and L²⁴ each, independently of one another, are H or F, and X⁰ ispreferably F. Particularly preferred are compounds of formulae A1 andA2.

Particularly preferred compounds of formula A1 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula A1, L²³,L²⁴, L²⁵ and L²⁶ are each, independently of one another, H or F, and X⁰is preferably F.

Very particularly preferred compounds of formula A1 are selected fromthe group consisting of the following subformulae:

In which R²¹ is as defined in formula A1.

Particularly preferred compounds of formula A2 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula A2, L²³,L²⁴, L²⁵ and L²⁶ each, independently of one another, are H or F, and X⁰is preferably F.

Very particularly preferred compounds of formula A2 are selected fromthe group consisting of the following subformulae:

in which R²¹ and X⁰ are as defined in formula A2.

Particularly preferred compounds of formula A3 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula A3, andX⁰ is preferably F.

Particularly preferred compounds of formula A4 are selected from thegroup consisting of the following subformulae:

in which R²¹ is as defined in formula A4.

Preferably component B) of the LC medium comprises one or more compoundsof formula B selected from the group consisting of the followingformulae:

in which g, A³¹, A³², R³¹, X⁰, L³¹ and L³² have the meanings given informula B, and X⁰ is preferably F. Particularly preferred are compoundsof formulae B1 and B2.

Particularly preferred compounds of formula B1 are selected from thegroup consisting of the following subformulae:

in which R³¹, X⁰, L³¹ and L³² have the meaning given in formula B1, andX⁰ is preferably F.

Very particularly preferred compounds of formula B1a are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B1.

Very particularly preferred compounds of formula B1b are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B1.

Particularly preferred compounds of formula B2 are selected from thegroup consisting of the following subformulae:

in which R³¹, X⁰, L³¹ and L³² have the meaning given in formula B2, L³³,L³⁴, L³⁵ and L³⁶ are each, independently of one another, H or F, and X⁰is preferably F.

Very particularly preferred compounds of formula B2 are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2b are selected fromthe group consisting of the following subformulae

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2c are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2d and B2e areselected from the group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2f are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.Very particularly preferred compounds of formula B2g are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2h are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2i are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B2k are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Very particularly preferred compounds of formula B21 are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula B2.

Alternatively to, or in addition to, the compounds of formula B1 and/orB2 component B) of the LC medium may also comprise one or more compoundsof formula B3 as defined above.

Particularly preferred compounds of formula B3 are selected from thegroup consisting of the following subformulae:

in which R³¹ is as defined in formula B3.

Preferably component B) of the LC medium comprises, in addition to thecompounds of formula A and/or B, one or more compounds of formula C

in which the individual radicals have the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

-   R⁴¹, R⁴² each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   Z⁴¹, Z⁴² each, independently of one another, —CH₂CH₂—, —COO—,    trans-CH═CH—, trans-CF═CF—, —CH₂O—, —CF₂O—, —C═C— or a single bond,    preferably a single bond,-   h 0, 1, 2 or 3.

In the compounds of formula C, R⁴¹ and R⁴² are preferably selected fromstraight-chain alkyl or alkoxy with 1, 2, 3, 4, 5 or 6 C atoms, andstraight-chain alkenyl with 2, 3, 4, 5, 6 or 7 C atoms.

In the compounds of formula C, h is preferably 0, 1 or 2.

In the compounds of formula C, Z⁴¹ and Z⁴² are preferably selected fromCOO, trans-CH═CH and a single bond, very preferably from COO and asingle bond.

Preferred compounds of formula C are selected from the group consistingof the following subformulae:

wherein R⁴¹ and R⁴² have the meanings given in formula C, and preferablydenote each, independently of one another, alkyl, alkoxy, fluorinatedalkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy,alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms.

Further preferably component B) of the LC medium comprises, in additionto the compounds of formula A and/or B, one or more compounds of formulaD

in which A⁴¹, A⁴², Z⁴¹, Z⁴², R⁴¹, R⁴² and h have the meanings given informula C or one of the preferred meanings given above.

Preferred compounds of formula D are selected from the group consistingof the following subformulae:

in which R⁴¹ and R⁴² have the meanings given in formula D and R⁴¹preferably denotes alkyl bedeutet, and in formula D1 R⁴² preferablydenotes alkenyl, particularly preferably —(CH₂)₂—CH═CH—CH₃, and informula D2 R⁴² preferably denotes alkyl, —(CH₂)₂—CH═CH₂ or—(CH₂)₂—CH═CH—CH₃.

Further preferably component B) of the LC medium comprises, in additionto the compounds of formula A and/or B, one or more compounds of formulaE containing an alkenyl group

in which the individual radicals, on each occurrence identically ordifferently, each, independently of one another, have the followingmeaning:

-   R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the    rings X, Y and Z denotes cyclohexenyl, also one of the meanings of    R^(A2),-   R^(A2) alkyl having 1 to 12 C atoms, in which, in addition, one or    two non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,    —OCO— or —COO— in such a way that O atoms are not linked directly to    one another,-   x 1 ort.

R^(A2) is preferably straight-chain alkyl or alkoxy having 1 to 8 Catoms or straight-chain alkenyl having 2 to 7 C atoms.

Preferred compounds of formula E are selected from the followingsubformulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very preferred compounds of the formula E are selected from thefollowing sub-formulae:

in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, andR^(b1) denotes H, CH₃ or C₂H₅.

Very particularly preferred compounds of the formula E are selected fromthe following sub-formulae:

Most preferred are compounds of formula E1a2, E1a5, E3a1 and E6a1.

Further preferably component B) of the LC medium comprises, in additionto the compounds of formula A and/or B, one or more compounds of formulaF

in which the individual radicals have, independently of each other andon each occurrence identically or differently, the following meanings:

denote

-   R²¹, R³¹ each, independently of one another, alkyl, alkoxy, oxaalkyl    or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having    2 to 9 C atoms, all of which are optionally fluorinated,-   X⁰ F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   Z²¹ —CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O— or    a single bond, preferably —CH₂CH₂—, —COO—, trans-CH═CH— or a single    bond, particularly preferably —COO—, trans-CH═CH— or a single bond,-   L²¹, L²², L²³, L²⁴ each, independently of one another, H or F,-   g 0, 1, 2 or 3.

Particularly preferred compounds of formula F are selected from thegroup consisting of the following formulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula F, L²⁵and L²⁶ are each, independently of one another, H or F, and X⁰ ispreferably F.

Very particularly preferred compounds of formula F1-F3 are selected fromthe group consisting of the following subformulae:

In which R²¹ is as defined in formula F1.

The concentration of the compounds of formula A and B in the LC hostmixture is preferably from 2 to 60%, very preferably from 3 to 45%, mostpreferably from 4 to 35%.

The concentration of the compounds of formula C and D in the LC hostmixture is preferably from 2 to 70%, very preferably from 5 to 65%, mostpreferably from 10 to 60%.

The concentration of the compounds of formula E in the LC host mixtureis preferably from 5 to 50%, very preferably from 5 to 35%.

The concentration of the compounds of formula F in the LC host mixtureis preferably from 2 to 30%, very preferably from 5 to 20%.

Further preferred embodiments of this second preferred embodiment of thepresent invention are listed below, including any combination thereof.

-   2a) The LC host mixture comprises one or more compounds of formula A    and/or B with high positive dielectric anisotropy, preferably with    Δε>15.-   2b) The LC host mixture comprises one or more compounds selected    from the group consisting of formulae A1a2, A1b1, A1d1, A1f1, A2a1,    A2h1, A2l2, A2k1, B2h3, B2l1, F1a. The proportion of these compounds    in the LC host mixture is preferably from 4 to 40%, very preferably    from 5 to 35%.-   2c) The LC host mixture comprises one or more compounds selected    from the group consisting of formulae B2c1, B2c4, B2f4, C14. The    proportion of these compounds in the LC host mixture is preferably    from 4 to 40%, very preferably from 5 to 35%.-   2d) The LC host mixture comprises one or more compounds selected    from the group consisting of formulae C3, C4, C5, C9 and D2. The    proportion of these compounds in the LC host mixture is preferably    from 8 to 70%, very preferably from 10 to 60%.-   2e) The LC host mixture comprises one or more compounds selected    from the group consisting of formulae G1, G2 and G5, preferably G1a,    G2a and G5a. The proportion of these compounds in the LC host    mixture is preferably from 4 to 40%, very preferably from 5 to 35%.-   2f) The LC host mixture comprises one or more compounds selected    from the group consisting of formulae E1, E3 and E6, preferably E1a,    E3a and E6a, very preferably E1a2, E1a5, E3a1 and E6a1. The    proportion of these compounds in the LC host mixture is preferably    from 5 to 60%, very preferably from 10 to 50%.

The combination of compounds of the preferred embodiments mentionedabove with the polymerised compounds described above causes lowthreshold voltages, low rotational viscosities and very goodlow-temperature stabilities in the LC media according to the inventionat the same time as constantly high clearing points and high HR values,and allows the rapid establishment of a particularly low pretilt anglein PSA displays. In particular, the LC media exhibit significantlyshortened response times, in particular also the grey-shade responsetimes, in PSA displays compared with the media from the prior art.

The LC media and LC host mixtures of the present invention preferablyhave a nematic phase range of at least 80 K, particularly preferably atleast 100 K, and a rotational viscosity ≤250 mPa·s, preferably ≤200mPa·s, at 20° C.

In the VA-type displays according to the invention, the molecules in thelayer of the LC medium in the switched-off state are alignedperpendicular to the electrode surfaces (homeotropically) or have a atilted homeotropic alignment. On application of an electrical voltage tothe electrodes, a realignment of the LC molecules takes place with thelongitudinal molecular axes parallel to the electrode surfaces.

LC media according to the invention based on compounds with negativedielectric anisotropy according to the first preferred embodiment, inparticular for use in displays of the PS-VA, PS-UB-FFS and SA-VA type,have a negative dielectric anisotropy Δε, preferably from −0.5 to −10,in particular from −2.5 to −7.5, at 20° C. and 1 kHz.

The birefringence Δn in LC media according to the invention for use indisplays of the PS-VA, PS-UB-FFS and SA-VA type is preferably below0.16, particularly preferably from 0.06 to 0.14, very particularlypreferably from 0.07 to 0.12.

In the OCB-type displays according to the invention, the molecules inthe layer of the LC medium have a “bend” alignment. On application of anelectrical voltage, a realignment of the LC molecules takes place withthe longitudinal molecular axes perpendicular to the electrode surfaces.

LC media according to the invention, based on compounds with positivedielectric anisotropy according to the second preferred embodiment, foruse in displays of the PS-TN-, PS-posi-VA-, PS-IPS-, PS-FFS and SA-FFStype, preferably have a positive dielectric anisotropy Δε from +2 to+30, particularly preferably from +3 to +20, at 20° C. and 1 kHz.

The birefringence Δn in LC media according to the invention for use indisplays of the PS-OCB type is preferably from 0.14 to 0.22,particularly preferably from 0.16 to 0.22.

The birefringence Δn in LC media according to the invention for use indisplays of the PS-TN-, PS-posi-VA-, PS-IPS-, PS-FFS and SA-FFS type ispreferably from 0.07 to 0.15, particularly preferably from 0.08 to 0.13.

The LC media according to the invention may also comprise furtheradditives which are known to the person skilled in the art and aredescribed in the literature, such as, for example, polymerisationinitiators, inhibitors, stabilisers, surface-active substances or chiraldopants. These may be polymerisable or non-polymerisable. Polymerisableadditives are accordingly ascribed to the polymerisable component orcomponent A). Non-polymerisable additives are accordingly ascribed tothe non-polymerisable component or component B).

In a preferred embodiment the LC media contain one or more chiraldopants, preferably in a concentration from 0.01 to 1%, very preferablyfrom 0.05 to 0.5%. The chiral dopants are preferably selected from thegroup consisting of compounds from Table B below, very preferably fromthe group consisting of R- or S-1011, R- or S-2011, R- or S-3011, R- orS-4011, and R- or S-5011.

In another preferred embodiment the LC media contain a racemate of oneor more chiral dopants, which are preferably selected from the chiraldopants mentioned in the previous paragraph.

In another preferred embodiment the LC medium according to the presentinvention contains a self-aligning (SA) additive, preferably in aconcentration of 0.1 to 2.5%. An LC medium according to this preferredembodiment is especially suitable for use in polymer stabilised SA-VAand SA-FFS displays.

In a preferred embodiment the SA-VA or SA-FFS display according to thepresent invention does not contain a polyimide alignment layer. Inanother preferred embodiment the SA-VA or SA-FFS display according topreferred embodiment contains a polyimide alignment layer.

Preferred SA additives for use in this preferred embodiment are selectedfrom compounds comprising a mesogenic group and a straight-chain orbranched alkyl side chain that is terminated with one or more polaranchor groups selected from hydroxy, carboxy, amino or thiol groups.

Further preferred SA additives contain one or more polymerisable groupswhich are attached, optionally via spacer groups, to the mesogenicgroup. These polymerisable SA additives can be polymerised in the LCmedium under similar conditions as applied for the RMs in the PSAprocess.

Suitable SA additives to induce homeotropic alignment, especially foruse in SA-VA mode displays, are disclosed for example in US 2013/0182202A1, US 2014/0838581 A1, US 2015/0166890 A1 and US 2015/0252265 A1.

In another preferred embodiment an LC medium or a polymer stabilisedSA-VA or SA-FFS display according to the present invention contains oneor more self-aligning additives selected from Table E below.

Furthermore, it is possible to add to the LC media, for example, 0 to15% by weight of pleochroic dyes, furthermore nanoparticles, conductivesalts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate,tetrabutylammonium tetraphenylborate or complex salts of crown ethers(cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258(1973)), for improving the conductivity, or substances for modifying thedielectric anisotropy, the viscosity and/or the alignment of the nematicphases. Substances of this type are described, for example, in DE-A 2209 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53728.

The individual components of the preferred embodiments a)-z) of the LCmedia according to the invention are either known or methods for thepreparation thereof can readily be derived from the prior art by theperson skilled in the relevant art, since they are based on standardmethods described in the literature. Corresponding compounds of theformula CY are described, for example, in EP-A-0 364 538. Correspondingcompounds of the formula ZK are described, for example, in DE-A-26 36684 and DE-A-33 21 373.

The LC media which can be used in accordance with the invention areprepared in a manner conventional per se, for example by mixing one ormore of the above-mentioned compounds with one or more polymerisablecompounds as defined above, and optionally with furtherliquid-crystalline compounds and/or additives. In general, the desiredamount of the components used in lesser amount is dissolved in thecomponents making up the principal constituent, advantageously atelevated temperature. It is also possible to mix solutions of thecomponents in an organic solvent, for example in acetone, chloroform ormethanol, and to remove the solvent again, for example by distillation,after thorough mixing. The invention furthermore relates to the processfor the preparation of the LC media according to the invention.

It goes without saying to the person skilled in the art that the LCmedia according to the invention may also comprise compounds in which,for example, H, N, O, Cl, F have been replaced by the correspondingisotopes like deuterium etc.

The following examples explain the present invention without restrictingit. However, they show the person skilled in the art preferred mixtureconcepts with compounds preferably to be employed and the respectiveconcentrations thereof and combinations thereof with one another. Inaddition, the examples illustrate which properties and propertycombinations are accessible.

Preferred mixture components are shown in Tables A1 and A2 below. Thecompounds shown in Table A1 are especially suitable for use in LCmixtures with positive dielectric anisotropy. The compounds shown inTable A2 are especially suitable for use in LC mixtures with negativedielectric anisotropy.

TABLE A1 In Table A1, m and n are independently of each other an integerfrom 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6,and (O)C_(m)H_(2m+1) means C_(m)H_(2m+1) or OC_(m)H_(2m+1).

APU-n-OXF

ACQU-n-F

APUQU-n-F

BCH-nF.F

BCH-nF.F.F

BCH-n.Fm

CFU-n-F

CBC-nm

CBC-nmF

CCOC-n-m

C-n-V

C-n-XF

C-n-m

CC-n-V

CC-n-Vm

CC-n-kVm

CC-nV-Vm

CCP-nV-m

CCP-Vn-m

CCG-V-F

CCVC-n-V

CCP-n-m

CP-nV-m

CP-Vn-m

CPPC-nV-Vm

CVCP-1V-OT

CLP-n-T

CLP-n-OT

CLP-nV-T

CLP-nV-OT

CLP-Vn-T

CLP-Vn-OT

CLP-nVm-T

CLP-nVm-OT

CLP-nVk-m

CPGP-n-m

CCP-nOCF₃

CCP-nF.F.F

CGG-n-F

CGU-n-F

CDU-n-F

DCU-n-F

CCGU-n-F

CPGU-n-F

CCPU-n-F

CPGU-n-OT

CCQU-n-F

CCQG-n-F

CUQU-n-F

CQU-n-F

CCCQU-n-F

CDUQU-n-F

CLUQU-n-F

CPPQU-n-F

CGUQU-n-F

CCZU-n-F

CGZP-n-OT

CPTU-n-F

GPTU-n-F

CPU-n-VT

CPU-n-AT

CPU-n-OXF

CWCG-n-F

CWCU-n-F

CWCQU-n-F

Dec-U-n-F

LPP-n-m

DPGU-n-F

DPGU-n-OT

DGUQU-n-F

DUUQU-n-F

ECCP-nm

ECCP-nOCF₃

GP-n-Cl

GGP-n-Cl

GGP-n-F

PGIGI-n-F

GPQU-n-F

GUQGU-n-F

PGU-n-OXF

MPP-n-F

MUQU-n-F

NUQU-n-F

PGU-n-F

PPGU-n-F

PQU-n-F

PUQU-n-F

PGUQU-n-F

PGP-n-m

PGP-n-kVm

PP-nV-Vm

PP-n-kVm

PCH-nOm

PCH-nCl

PYP-nF

TABLE A2 In Table A2, m and n are independently of each other an integerfrom 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6,and (O)C_(m)H_(2m+1) means C_(m)H_(2m+1) or OC_(m)H_(2m+1).

In a first preferred embodiment of the present invention, the LC mediaaccording to the invention, especially those with positive dielectricanisotropy, comprise one or more compounds selected from the groupconsisting of compounds from Table A1.

In a second preferred embodiment of the present invention, the LC mediaaccording to the invention, especially those with negative dielectricanisotropy, comprise one or more compounds selected from the groupconsisting of compounds from Table A2.

TABLE B Table B shows possible chiral dopants which can be added to theLC media according to the invention.

The LC media preferably comprise 0 to 10% by weight, in particular 0.01to 5% by weight, particularly preferably 0.1 to 3% by weight, ofdopants. The LC media preferably comprise one or more dopants selectedfrom the group consisting of compounds from Table B.

TABLE C Table C shows possible stabilisers which can be added to the LCmedia according to the invention. Therein n denotes an integer from 1 to12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups arenot shown.

The LC media preferably comprise 0 to 10% by weight, in particular 1 ppmto 5% by weight, particularly preferably 1 ppm to 1% by weight, ofstabilisers. The LC media preferably comprise one or more stabilisersselected from the group consisting of compounds from Table C.

TABLE D Table D shows illustrative reactive mesogenic compounds whichcan be used in the LC media in accordance with the present invention.

RM-1

RM-2

RM-3

RM-4

RM-5

RM-6

RM-7

RM-8

RM-9

RM-10

RM-11

RM-12

RM-13

RM-14

RM-15

RM-16

RM-17

RM-18

RM-19

RM-20

RM-21

RM-22

RM-23

RM-24

RM-25

RM-26

RM-27

RM-28

RM-29

RM-30

RM-31

RM-32

RM-33

RM-34

RM-35

RM-36

RM-37

RM-38

RM-39

RM-40

RM-41

RM-42

RM-43

RM-44

RM-45

RM-46

RM-47

RM-48

RM-49

RM-50

RM-51

RM-52

RM-53

RM-54

RM-55

RM-56

RM-57

RM-58

RM-59

RM-60

RM-61

RM 62

RM-63

RM-64

RM-65

RM-66

RM-67

RM-68

RM-69

RM-70

RM-71

RM-72

RM-73

RM-74

RM-75

RM-76

RM-77

RM-78

RM-79

RM-80

RM-81

RM-82

RM-83

RM-84

RM-85

RM-86

RM-87

RM-88

RM-89

RM-90

RM-91

RM-92

RM-93

RM-94

RM-95

RM-96

RM-97

RM-98

RM-99

RM-100

RM-101

RM-102

RM-103

RM-104

RM-105

RM-106

RM-107

RM-108

RM-109

RM-110

RM-111

RM-112

RM-113

RM-114

RM-115

RM-116

RM-117

RM-118

RM-119

RM-120

RM-121

RM-122

RM-123

RM-124

RM-125

RM-126

RM-127

RM-128

RM-129

RM-130

RM-131

RM-132

RM-133

RM-134

RM-135

RM-136

RM-137

RM-138

RM-139

RM-140

RM-141

RM-142

RM-143

In a preferred embodiment, the mixtures according to the inventioncomprise one or more polymerisable compounds, preferably selected fromthe polymerisable compounds of the formulae RM-1 to RM-140. Of these,compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM40,RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-102,RM-103, RM-109, RM-117, RM-120, RM-121 and RM-122 are particularlypreferred.

TABLE E Table E shows self-alignment additives for vertical alignmentwhich can be used in LC media for SA-VA and SA-FFS displays according tothe present invention together with the polymerizable compounds offormula I:

SA-1

SA-2

SA-3

SA-4

SA-5

SA-6

SA-7

SA-8

SA-9

SA-10

SA-11

SA-12

SA-13

SA-14

SA-15

SA-16

SA-17

SA-18

SA-19

SA-20

SA-21

SA-22

SA-23

SA-24

SA-25

SA-26

SA-27

SA-28

SA-29

SA-30

SA-31

SA-32

SA-33

SA-34

In a preferred embodiment, the LC media, SA-VA and SA-FFS displaysaccording to the present invention comprise one or more SA additivesselected from formulae SA-1 to SA-34, preferably from formulae SA-14 toSA-34, very preferably from formulae SA-20 to SA-28, most preferably offormula SA-20, in combination with one or more RMs of formula I. Verypreferred is a combination of polymerizable compound 1, 2 or 3 ofExample 1 below, very preferably of polymerizable compound 3 of Example1, with an SA additive of formula SA-20 to SA-28, very preferably offormula SA-20.

EXAMPLES

The following examples explain the present invention without restrictingit. However, they show the person skilled in the art preferred mixtureconcepts with compounds preferably to be employed and the respectiveconcentrations thereof and combinations thereof with one another. Inaddition, the examples illustrate which properties and propertycombinations are accessible.

In addition, the following abbreviations and symbols are used:

-   V₀ threshold voltage, capacitive [V] at 20° C.,-   n_(e) extraordinary refractive index at 20° C. and 589 nm,-   n_(o) ordinary refractive index at 20° C. and 589 nm,-   Δn optical anisotropy at 20° C. and 589 nm,-   ε_(⊥) dielectric permittivity perpendicular to the director at    20° C. and 1 kHz,-   ε_(∥) dielectric permittivity parallel to the director at 20° C. and    1 kHz,-   Δε dielectric anisotropy at 20° C. and 1 kHz,-   cl.p., T(N,I) clearing point [° C.],-   γ₁ rotational viscosity at 20° C. [mPa·s],-   K₁ elastic constant, “splay” deformation at 20° C. [pN],-   K₂ elastic constant, “twist” deformation at 20° C. [pN],-   K₃ elastic constant, “bend” deformation at 20° C. [pN].

Unless explicitly noted otherwise, all concentrations in the presentapplication are quoted in percent by weight and relate to thecorresponding mixture as a whole, comprising all solid orliquid-crystalline components, without solvents.

Unless explicitly noted otherwise, all temperature values indicated inthe present application, such as, for example, for the melting pointT(C,N), the transition from the smectic (S) to the nematic (N) phaseT(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (°C.). M.p. denotes melting point, cl.p.=clearing point. Furthermore,C=crystalline state, N=nematic phase, S=smectic phase and I=isotropicphase. The data between these symbols represent the transitiontemperatures.

All physical properties are and have been determined in accordance with“Merck Liquid Crystals, Physical Properties of Liquid Crystals”, StatusNovember 1997, Merck KGaA, Germany, and apply for a temperature of 20°C., and Δn is determined at 589 nm and Δε at 1 kHz, unless explicitlyindicated otherwise in each case.

The term “threshold voltage” for the present invention relates to thecapacitive threshold (V₀), also known as the Freedericks threshold,unless explicitly indicated otherwise. In the examples, the opticalthreshold may also, as generally usual, be quoted for 10% relativecontrast (V₁₀).

Unless stated otherwise, the process of polymerising the polymerisablecompounds in the PSA displays as described above and below is carriedout at a temperature where the LC medium exhibits a liquid crystalphase, preferably a nematic phase, and most preferably is carried out atroom temperature.

Unless stated otherwise, methods of preparing test cells and measuringtheir electrooptical and other properties are carried out by the methodsas described hereinafter or in analogy thereto.

The display used for measurement of the capacitive threshold voltageconsists of two plane-parallel glass outer plates at a separation of 25μm, each of which has on the inside an electrode layer and an unrubbedpolyimide alignment layer on top, which effect a homeotropic edgealignment of the liquid-crystal molecules.

The display or test cell used for measurement of the tilt anglesconsists of two plane-parallel glass outer plates at a separation of 4μm, each of which has on the inside an electrode layer and a polyimidealignment layer on top, where the two polyimide layers are rubbedantiparallel to one another and effect a homeotropic edge alignment ofthe liquid-crystal molecules.

The polymerisable compounds are polymerised in the display or test cellby irradiation with UV light of defined intensity for a prespecifiedtime, with a voltage simultaneously being applied to the display(usually 10 V to 30 V alternating current, 1 kHz). In the examples,unless indicated otherwise, a metal halide lamp and an intensity of 100mW/cm² is used for polymerisation.

The intensity is measured using a standard meter (Hoenle UV-meter highend with UV sensor).

The tilt angle is determined using the Mueller Matrix Polarimeter“AxoScan” from Axometrics. A low value (i.e. a large deviation from the90° angle) corresponds to a large tilt here.

Unless stated otherwise, the term “tilt angle” means the angle betweenthe LC director and the substrate, and “LC director” means in a layer ofLC molecules with uniform orientation the preferred orientationdirection of the optical main axis of the LC molecules, whichcorresponds, in case of calamitic, uniaxially positive birefringent LCmolecules, to their molecular long axis.

Example 1: Polymerisable Compounds

Polymerisable compound (or “RM”) 1 is prepared as follows

1.4: A suspension of sodium hydride (5.4 g, 60% in mineral oil, 135.6mmol) was added to a stirred solution of benzyl alcohol 1.3 (20.0 g,113.0 mmol) in THF (20 mL) at 0° C. The resulting mixture was stirredfor 10 min at the same temperature before it was treated with methyliodide (8.7 mL, 135.6 mmol). The reaction mixture was stirred for 4hours at ambient temperature, carefully quenched with water andextracted with ethyl acetate. Aqueous phase was separated and extractedwith ethyl acetate (2 times). The combined organic phase was washed withsat. NaCl solution, dried over Na₂SO₄, filtered and concentrated invacuo. The residue was purified with flash chromatography (heptane) togive 1.4 as a colorless oil. (21.0 g, 97%; GC: 99.9%).

1.6: Hydrazine hydrate (0.2 mL, 80%, 0.004 mol) was added to a stirredsolution of sodium metaborate tetrahydrate (43.3 g, 0.314 mol) andPdCl₂[P(cy)₃]₂ (3.1 g, 0.004 mol) in THF (5 mL)/water (60 mL) at roomtemperature. The resulting mixture was stirred for 5 min at ambienttemperature before it was treated with a solution of 1.4 (20.0 g, 0.105mol) and 1.5 (74.9 g, 0.199 mol) in THF (520 mL). The reaction mixturewas stirred overnight at 70° C., phases separated and the aqueous phasewas extracted with methyl tert-butyl ether (2 times). The combinedorganics were washed with water, dried over Na₂SO₄, filtered andconcentrated in vacuo. The residue (67.0 g, 103%) was used in the nextstep without further purification.

1.7: A solution of TBAF (in THF, 1.0 M, 158 mL, 158 mmol) was addeddropwise to a stirred solution of 1.6 (42.0 g, 67.8 mmol) in THF (500mL) at 5° C. The resulting mixture was stirred 30 min at 3° C., followedby 1 h at ambient temperature, before it was poured on 40 mL ice,acidified with HCl (2.0 M) until pH=6 and extracted with ethyl acetate(3 times). The combined organic phase was washed with sat. NaClsolution, dried over Na₂SO₄, filtered and concentrated in vacuo. Theresidue was purified with flash chromatography(dichloromethane/methanol) to give 1.7 as white crystals (9.6 g, 46%).

1: Methacrylic acid (6.7 g, 78.3 mmol) and 4-dimethylaminopyridine(DMAP, 0.38 g, 3.1 mmol) were added to a stirred solution of biphenol1.7 (9.6 g, 31.1 mmol) in dichloromethane (150 mL) at room temperature.The resulting mixture was cooled to 3° C. followed by dropwise addition1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (12.2 g, 78.3 mmol) indichloromethane (20 mL). The reaction mixture was allowed to warm toroom temperature and stirred overnight, before it was concentrated invacuo. The residue was purified by flash chromatography (heptane/ethylacetate) and recrystallized from heptane/ethanol (2:1) to give 1 aswhite crystals (10.2 g, 74%; HPLC: 99.7%). ¹H NMR (CDCl₃): 2.12-2.13 (m,6H), 3.41 (s, 3H), 4.43 (s, 2H), 5.80-5.82 (m, 2H), 6.41-6.42 (m, 2H),7.27-7.21 (m, 4H), 7.40 (d, J=7.9 Hz, 1H), 7.45-7.49 (m, 2H), 7.60 (dd,J=7.9, 2.0 Hz, 1H), 7.74-7.65 (m, 2H), 7.78 (d, J=1.9 Hz, 1H); EI-MS:442.0.

DSC: Tg 0 K 117 I.

In analogy to polymerizable compound 1, the following compounds havebeen synthesized:

2: Melting Point: 117° C. ¹H NMR (CDCl₃): δ 7.76 (d, J=2.3 Hz, 1H),7.72-7.66 (m, 6H), 7.62 (dd, J=8.3, 2.4 Hz, 1H), 7.27-7.22 (m, 3H), 6.42(dt, J=8.0, 1.2 Hz, 2H), 5.82 (dp, J=7.9, 1.6 Hz, 2H), 4.51 (s, 2H),3.43 (s, 3H), 2.13 (t, J=1.2 Hz, 3H), 2.12 (t, J=1.3 Hz, 3H). EI-MS:442.2

3: Melting Point: 74° C. ¹H NMR (CDCl₃): δ 7.69 (d, J=2.3 Hz, 1H),7.65-7.61 (m, 2H), 7.55 (dd, J=8.3, 2.4 Hz, 1H), 7.26-7.19 (m, 3H), 6.41(dt, J=8.3, 1.2 Hz, 2H), 5.81 (dt, J=8.3, 1.6 Hz, 2H), 4.49 (s, 2H),3.42 (s, 3H), 2.12 (t, J=1.3 Hz, 3H), 2.11 (t, J=1.2 Hz, 3H). EI-MS:366.0

Example 2: Polymerisable Mixtures

The nematic LC host mixture N1 is formulated as follows:

CCH-501  9.00% cl.p. 70.0° C. CCH-35 14.00% Δn   0.0825 PCH-53  8.00% Δε−3.5 CY-3-O4 14.00% ε_(∥)   3.5 CY-5-O4 13.00% K₃/K₁   1.00 CCY-2-1 9.00% γ₁   141 mPa s CCY-3-1  9.00% V₀  2.10 V CCY-3-O2  8.00% CCY-5-O2 8.00% CPY-2-O2  8.00%

The nematic LC host mixture N2 is formulated as follows:

CY-3-O2 18.00% cl.p. +74.5° C. CPY-2-O2 10.00% Δn   0.1021 CPY-3-O210.00% Δε −3.1 CCY-3-O2  9.00% ε_(∥)   3.5 CCY-4-O2  4.00% K₃/K₁   1.16PYP-2-3  9.00% γ₁      86 m Pa s CC-3-V 40.00% V₀    2.29 V

The nematic LC host mixture N3 is formulated as follows:

CC-3-V1  9.00% cl.p. CCH-23 14.00% Δn CCH-34  6.00% Δε CCH-35  6.00%ε_(∥) CCP-3-1  7.00% K₃/K₁ CCY-3-O1  5.00% γ₁ CCY-3-O2 10.00% V₀CPY-3-O2 12.00% CY-3-O2  9.50% PP-1-2V1  8.50% PY-3-O2 12.00% PY-4-O2 1.00%

Polymerisable mixtures P11, P21 and P31 according to the presentinvention are prepared by adding polymerisable compound RM1 of Example 1to nematic LC host mixture N1, N2 or N3, respectively.

For comparison purpose, polymerisable mixtures C11, C12, C21, C22, C31and C32 are prepared by adding RM C1 which has a biphenyl core and nosubstituent, or RM C2 which has a terphenyl core and a fluorinesubstituent, to nematic LC host mixture N1, N2 or N3, respectively.

The concentrations of the RMs in the polymerisable mixtures are selectedsuch that the molar amount is in each case 0.093 mmol per 10 g mixture.The compositions of the individual polymerisable mixtures are shown inTable 1.

TABLE 1 Polymerisable mixture composition Mix. No. C11 C12 P11 C21 C22P21 LC Host N1 N1 N1 N2 N2 N2 RM C1 C2 1 C1 C2 1 wt. % RM 0.300 0.4270.412 0.300 0.427 0.412 Mix. No. C31 C32 P31 LC Host N3 N3 N3 RM C1 C2 1wt. % RM 0.300 0.427 0.412 wt. % RM — 0.400 0.386 (tilt stability)

Example 3: Use Examples

The individual polymerisable mixtures are filled into PSA test cells,the RM is polymerised under application of a voltage, and severalproperties like residual RM content, VHR under UV stress, tilt anglegeneration and tilt angle stability are measured.

Residual RM Measurement

The polymerisation speed is measured by determining the residual contentof residual, unpolymerised RM (in % by weight) in the mixture after UVexposure with a given intensity and lamp spectrum after a given UVexposure time. The smaller the residual RM content after a given timeinterval, the faster the polymerization,

For this purpose the polymerisable mixtures are filled into electrooptictest cells made of soda lime glass coated with an approximately 200 nmthick layer of ITO and a 30 nm layer of VA-polyimide from Varitronixwith a cell gap of 6-7 μm

The test cells are illuminated by a MH-lamp (UV-Cube 2000) using a 320nm long pass filter (N-WG320) and a light intensity of 100 mW/cm²,causing polymerisation of the RM. Illumination times are given in thetables below.

After polymerization the test cells are opened, and the mixture isdissolved and rinsed out of the test cell with 2 ml ethyl methyl ketoneand analyzed by High Performance Liquid Chromatography (HPLC). Forbetter comparison, the results are given by % relative to the initial RMamount. Thus, at 0 min illumination time 100% of RM are still present,while after x min illumination time y % of the RM are still present. Theresults are shown in Table 2.

TABLE 2 Residual RM content Mixture UV Time/min 0 2 4 6 C11 residualRM/%_(rel) 100 80 63 53 C12 100 41 19 10 P11 100 67 42 22 Mixture UVTime/min 0 2 6 C21 residual RM/%_(rel) 100 49 19 C22 100 24 2 P21 100 408

From Table 2 it can be seen that, for polymerisable mixtures with RM1according to the invention, the residual RM amount is significantlylower and polymerisation is significantly faster compared topolymerisable mixtures with biphenyl RM C₁, whereas residual RM amountis only slightly higher and polymerisation slightly slower compared topolymerisable mixtures with fluorinated terphenyl RM C₂.

Voltage Holding Ratio (VHR)

For measuring the VHR the polymerisable mixtures are filled intoelectrooptic test cells which consist of two AF glass substrates with anapproximately 20 nm thick ITO layer and a 100 nm thick polyimide layer.

The VHR is measured at 100° C. with application of a voltage of 1 V/60Hz before and after illumination. The sun-test consists of 2 hillumination by a Xenon lamp type Atlas Suntest CPS+ with a lightintensity of 765 W/m² at 20° C. The UV test consists of 10 minillumination by a metal halide lamp (UV cube 2000) using a 320 nm longpass filter (N-WG320) and a light intensity of 100 mW/cm² at 20° C.

The difference in VHR between the different RMs, based on RM 01 isexpressed according to:ΔVHR=VHR_(RM)−VHR_(RM-C1)

A positive value corresponds to an improvement in VHR with respect tothe reference RM C1, a negative value represents a decrease in VHR withrespect to the reference.

The results are shown in Table 3.

TABLE 3 VHR values Δ VHR (%) Mixture no illumination 2 h Suntest C11 0 0C12 0 −2 P11 0 0 Δ VHR (%) Mixture no illumination 2 h Suntest 10 min UVC21 0 0 0 C22 0 −4 −2 P21 0 0 0

From Table 3 it can be seen that RM1 according to the invention is ableto maintain the VHR level of the reference RM C1, and is able to providehigher VHR stability than fluorinated terphenyl RM C2.

Tilt Angle Generation

For measuring the tilt angle generation the polymerisable mixtures arefilled into electrooptic test cells made of two soda-lime glasssubstrates coated with an ITO electrode layer of approx. 200 nmthickness and a VA-polyimide alignment layer (JALS-2096-R1) of approx.30 nm thickness which is rubbed antiparallel. The cell gap is approx. 4μm.

The test cells are illuminated by a MH-lamp (UV-Cube 2000) using a 320nm long pass filter (N-WG320) and a light intensity of 100 mW/cm² at 20°C. with an applied square voltage of 24 V_(RMS) (alternating current, 1khz), causing polymerisation of the RM and a generation of a tilt angle.Illumination times are given in the respective tables. The generatedtilt was measured after a period of time of 12 hours using the MuellerMatrix Polarimeter “AxoScan” from Axometrics. The results are shown inTable 4.

TABLE 4 Tilt angle Mixture UV Time/min  0  2  6 C11 Tilt/° 90 85 78 C1288 76 71 P11 88 79 71 Mixture UV Time/min  0  2  6 C21 Tilt/° 89 77 70C22 89 82 79 P21 90 77 73

From Table 4 it can be seen that, in LC host N1 with RM1 according tothe invention, the tilt angle generation does initially proceed fasterbut remains at a higher angle compared to LC host N1 with biphenyl RMC1, but is similar to LC host N1 with fluorinated terphenyl RM C2.

In LC host N2 with RM1 according to the invention, the tilt anglegeneration does initially proceed faster but remains at a higher anglecompared to LC host N1 with fluorinated terphenyl RM C2, but is similarto LC host N1 with biphenyl RM C1.

Tilt Stability

For the tilt stability measurements the RMs C2 and RM1 are used inconcentrations corresponding to 0.087 mmol per 10 g of host mixture N3,as shown in Table 1 above.

The mixtures are filled into test cells made of soda lime glass coatedwith a 200 nm layer of ITO and a 30 nm layer of poly imide(JALS-2096-R1) were used. The polyimide layers are rubbed anti parallelto each other. Cellgap is approx. 4 μm.

The tilt is generated via illumination by a metal halide lamp (UV-Cube2000) using a 320 nm long pass filter (N-WG320) and a light intensity of100 mW/cm² at 20° C. with an applied square voltage of 10 V_(RMS) (1khz). The generated tilt is measured after a period of time of 12 hoursusing the Mueller Matrix Polarimeter “AxoScan” from Axometrics.

For RM C2 a pre-tilt of 84.8° was generated in N3 and for RM1 a tiltangle of 87.5° was generated in N3. Then the cells were electricallystressed with a square wave of 10 V_(RMS) at 1 khz frequency for 168 hat 40° C. After a relaxation time of 10-20 min the tilt angles weremeasured again. The results are shown below in Table 5 according to thefollowing equation:tilt_(after stress)−tilt_(after tilt generation)=Δ−tilt

The closer this value gets to 0, the more stable is the generated tilt.A high tilt stability is also an indicator for reduced image sticking inthe display.

TABLE 5 Tilt Stability Mixture Δ Tilt/° P31 0.3 C32 0.5

From Table 5 it can be seen that the generated tilt is more stable incase of RM1 compared to fluorinated terphenyl RM C2.

Overall the above results demonstrate that the RMs according to thepresent invention enable a fast UV-curing with complete polymerisationwhile maintaining a low ion content and high VHR in the mixture afterUV-processing, and enable fast and strong tilt angle generation withhigh tilt stability after electrical stress.

Thus, the RMs according to the present invention combines very fastpolymerisation speed similar to that terphenyl RMs with reliabilityparameters similar to biphenyl RMs, and thus show a superior overallperformance compared to RMs of prior art.

The invention claimed is:
 1. A compound of formula IP-Sp-A¹-(Z¹-A²)_(z)-R  I wherein the individual radicals, independentlyof each other and on each occurrence identically or differently, havethe following meanings P is a polymerisable group, Sp is a spacer groupor a single bond, A¹-(Z-A²)_(z)- is selected from the following formulae

wherein at least one benzene ring is substituted by exactly one groupL¹¹ and the benzene rings are optionally further substituted by one ormore groups L or P-Sp- L¹¹ is —CH₂—O—CH₃, R is P-Sp-, L is F, Cl, —CN,P-Sp- or straight chain alkyl having 1 to 25 C atoms, branched alkylhaving 3 to 25 C atoms, or cyclic alkyl having 3 to 25 C atoms, whereinone or more non-adjacent CH₂-groups of the straight, branched or cyclicalkyl groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—,—O—CO—O— in such a manner that O- and/or S-atoms are not directlyconnected with each other, and wherein one or more H atoms are eachoptionally replaced by P-Sp-, F or Cl, z is 0, 1, 2 or 3, with theproviso that at least one group Sp is a single bond.
 2. A compoundselected from the following formulae:

wherein R is H, L is F, Cl, —CN, P-Sp- or straight chain alkyl having 1to 25 C atoms, branched alkyl having 3 to 25 C atoms, or cyclic alkylhaving 3 to 25 C atoms, wherein one or more non-adjacent CH2-groups ofthe straight, branched or cyclic alkyl groups are optionally replaced by—O—, —S—, —CO—, —OO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/orS-atoms are not directly connected with each other, and wherein one ormore H atoms are each optionally replaced by P-Sp-, F or Cl, r1, r3, r6are independently of each other 0, 1, 2 or 3, r1, r3, r6 areindependently of each other 0, 1, 2 or 3, r2 is 0, 1, 2, 3 or 4, r4 andr5 are independently of each other 0, 1 or 2, wherein r1+r6≥1,r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1 and at least one group L denotes—CH₂—O—CH₃, and wherein at least one benzene ring is substituted byexactly one-CH₂—O—CH₃ group and wherein at least one of the groups Sp isa single bond.
 3. The compound according to claim 1, which is selectedfrom the following subformulae:

wherein P, Sp, P(Sp)₂, L, have the meanings given in claim 1 and r1, r3,r6 are independently of each other 0, 1, 2 or 3, r2 is 0, 1, 2, 3 or 4,r4, r5, r6 are independently of each other 0, 1 or 2, wherein r1+r6≥1,r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1, and at least one group L denotes—CH₂—O—CH₃, and wherein at least one of the groups Sp is a single bond.4. The compound according to claim 1, wherein P denotes acrylate ormethacrylate.
 5. The compound according to claim 1, wherein Sp is asingle bond or denotes —(CH₂)_(p2)—, —(CH₂)_(p2)—O—, —(CH₂)_(p2)—CO—O—,—(CH₂)_(p2)—O—CO—, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or theCO-group, respectively, is connected to the benzene ring.
 6. A liquidcrystal (LC) medium comprising one or more polymerisable compounds offormula I as defined in claim
 1. 7. The LC medium, characterized in thatit comprises a polymerisable component A) comprising one or morepolymerisable compounds of formula I as defined in claim 1, and aliquid-crystalline LC component B) comprising one or more mesogenic orliquid-crystalline compounds.
 8. The LC medium of claim 6, characterizedin that it additionally comprises one or more compounds of the formulaeCY and/or PY:

in which the individual radicals have the following meanings: a denotes1 or 2, b denotes 0 or 1,

denotes

R¹ and R² each, independently of one another, denote alkyl having 1 to12 C atoms, where, in addition, one or two non-adjacent CH₂ groups maybe replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that Oatoms are not linked directly to one another, Z^(x) denotes —CH═CH—,—CH₂O—, —OCH₂—, —CF₂O—, —OCF₂—, —O—, —CH₂—, —CH₂CH₂— or a single bond,L¹⁻⁴ each, independently of one another, denote F, Cl, OCF₃, CF₃, CH₃,CH₂F, CHF₂.
 9. The LC medium according to claim 6, characterized in thatit additionally comprises one or more compounds selected from thefollowing formulae:

in which the individual radicals, on each occurrence identically ordifferently, each, independently of one another, have the followingmeaning:

R^(A1) is alkenyl having 2 to 9 C atoms or, if at least one of the ringsX, Y and Z denotes cyclohexenyl, also one of the meanings of R^(A2),R^(A2) is alkyl having 1 to 12 C atoms, in which, in addition, one ortwo non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—, —OCO—or —COO— in such a way that O atoms are not linked directly to oneanother, Z^(x) is —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,—CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O—, or a single bond, L¹⁻⁴each, independently of one another, is H, F, Cl, OCF₃, CF₃, CH₃, CH₂F orCHF₂H, x is 1 or 2, z is 0 or
 1. 10. The LC medium according to claim 6,characterized in that it additionally comprises one or more compounds ofthe following formula:

in which the individual radicals have the following meanings:

denotes

denotes

R³ and R⁴ each, independently of one another, denote alkyl having 1 to12 C atoms, in which, in addition, one or two non-adjacent CH₂ groupsmay be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a waythat O atoms are not linked directly to one another, Z^(y) denotes—CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —COO—, —OCO—, —C₂F₄—,—CF═CF— or a single bond.
 11. The LC medium according to claim 6,characterized in that the polymerisable compounds of formula I arepolymerised.
 12. A process of preparing an LC medium of claim 7,comprising the steps of mixing one or more mesogenic orliquid-crystalline compounds with one or more compounds of formula I,and optionally with further liquid-crystalline compounds and/oradditives.
 13. An LC display comprising one or more compounds of formulaI as defined in claim
 1. 14. The LC display of claim 13, which is a PSAdisplay.
 15. The LC display of claim 14, which is a PS-VA, PS-OCB,PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA, PS-TN, polymer stabilised SA-VAor polymer stabilised SA-FFS display.
 16. A LC display comprising twosubstrates, at least one which is transparent to light, an electrodeprovided on each substrate or two electrodes provided on only one of thesubstrates, and located between the substrates a layer of an LC medium,comprising one or more polymerisable compounds, as defined in claim 6,wherein the polymerisable compounds are polymerised between thesubstrates of the display.
 17. A process for the production of an LCdisplay comprising the steps of providing an LC medium comprising one ormore polymerisable compounds, as defined in claim 6, between thesubstrates of the display, and polymerising the polymerisable compounds.18. A compound of formula IIPg-Sp-A¹-(Z¹-A²)_(z)-R*  II wherein Pg denotes OH, a protected hydroxylgroup or a masked hydroxyl group, R* denotes R or Pg-Sp-, and Sp,A¹-(Z-A²)_(z)- and R have the meanings given in claim
 1. 19. A processfor preparing a compound of formula I according to claim 1, byesterification of a compound of formula II,Pg-Sp-A¹-(Z¹-A²)_(z)-R*  II, wherein Pg denotes OH, R* denotes R orPg-Sp- and Sp, A¹-(Z-A²)_(z)- and R have the meanings given in claim 1,using corresponding acids, acid derivatives, or halogenated compoundscontaining a group P, as defined in claim 1, in the presence of adehydrating reagent.